diff --git a/tools/transpiler/src/ast/named_params.js b/tools/transpiler/src/ast/named_params.js
deleted file mode 100644
index 3bbc19a5dd..0000000000
--- a/tools/transpiler/src/ast/named_params.js
+++ /dev/null
@@ -1,16 +0,0 @@
-import {ParseTree} from 'traceur/src/syntax/trees/ParseTree';
-
-export class NamedParams extends ParseTree {
-  constructor(location, propertyNameAndValues) {
-    this.location = location;
-    this.propertyNameAndValues = propertyNameAndValues;
-  }
-
-  visit(visitor) {
-    visitor.visitNamedParamsExpression(this);
-  }
-
-  transform(transformer) {
-    return this;
-  }
-}
diff --git a/tools/transpiler/src/ast/object_pattern_binding_element.js b/tools/transpiler/src/ast/object_pattern_binding_element.js
deleted file mode 100644
index 6bcbf67bf2..0000000000
--- a/tools/transpiler/src/ast/object_pattern_binding_element.js
+++ /dev/null
@@ -1,7 +0,0 @@
-import {BindingElement} from 'traceur/src/syntax/trees/ParseTrees';
-
-export class ObjectPatternBindingElement extends BindingElement {
-  visit(visitor) {
-    visitor.visitObjectPatternBindingElement(this);
-  }
-}
diff --git a/tools/transpiler/src/codegeneration/NamedParamsTransformer.js b/tools/transpiler/src/codegeneration/NamedParamsTransformer.js
index 9dbae8c25c..22bd7b4a3f 100644
--- a/tools/transpiler/src/codegeneration/NamedParamsTransformer.js
+++ b/tools/transpiler/src/codegeneration/NamedParamsTransformer.js
@@ -1,12 +1,15 @@
-import {ParseTreeTransformer} from 'traceur/src/codegeneration/ParseTreeTransformer';
+import {ParseTreeTransformer} from './ParseTreeTransformer';
+
 import {
   BINDING_ELEMENT,
   OBJECT_PATTERN,
   OBJECT_LITERAL_EXPRESSION
 } from 'traceur/src/syntax/trees/ParseTreeType';
 
-import {NamedParams} from '../ast/named_params';
-import {ObjectPatternBindingElement} from '../ast/object_pattern_binding_element';
+import {
+  NamedParameterList,
+  ObjectPatternBindingElement
+} from '../syntax/trees/ParseTrees';
 
 /**
  * Transforms maps into named parameters:
@@ -22,6 +25,8 @@ import {ObjectPatternBindingElement} from '../ast/object_pattern_binding_element
  */
 export class NamedParamsTransformer extends ParseTreeTransformer {
   /**
+   * Transform function calls.
+   *
    * @param {CallExpression} tree
    * @return {ParseTree}
    */
@@ -58,10 +63,12 @@ export class NamedParamsTransformer extends ParseTreeTransformer {
   _replaceLastArgWithNamedParams(tree) {
     var args = tree.args.args;
     var last = this._last(args);
-    args[args.length - 1] = new NamedParams(last.location, last.propertyNameAndValues);
+    args[args.length - 1] = new NamedParameterList(last.location, last.propertyNameAndValues);
   }
 
   /**
+   * Transform function declaration.
+   *
    * @param {ObjectPattern} tree
    * @return {ParseTree}
    */
diff --git a/tools/transpiler/src/codegeneration/ParseTreeTransformer.js b/tools/transpiler/src/codegeneration/ParseTreeTransformer.js
index 449de13c6b..d052bc0cb1 100644
--- a/tools/transpiler/src/codegeneration/ParseTreeTransformer.js
+++ b/tools/transpiler/src/codegeneration/ParseTreeTransformer.js
@@ -4,7 +4,9 @@ import {
 
 import {
   ClassFieldDeclaration,
-  PropertyConstructorAssignment
+  PropertyConstructorAssignment,
+  NamedParameterList,
+  ObjectPatternBindingElement
 } from '../syntax/trees/ParseTrees'
 
 export class ParseTreeTransformer extends TraceurParseTreeTransformer {
@@ -28,4 +30,21 @@ export class ParseTreeTransformer extends TraceurParseTreeTransformer {
       tree.name, tree.parameterList, tree.typeAnnotation, tree.annotations, tree.body, tree.isConst,
       initializerList);
   }
-}
\ No newline at end of file
+
+  transformNamedParameterList(tree) {
+    var nvPairs = this.transformList(tree.parameterNameAndValues);
+    if (nvPairs === tree.parameterNameAndValues) {
+      return tree;
+    }
+    return new NamedParameterList(tree.location, nvPairs);
+  }
+
+  transformObjectPatternBindingElement(tree) {
+    var binding = this.transformAny(tree.binding);
+    var initializer = this.transformAny(tree.initializer);
+    if (binding === tree.binding && initializer === tree.initializer) {
+      return tree;
+    }
+    return new ObjectPatternBindingElement(tree.location, binding, initializer);
+  }
+}
diff --git a/tools/transpiler/src/outputgeneration/DartParseTreeWriter.js b/tools/transpiler/src/outputgeneration/DartParseTreeWriter.js
index d60b5da845..e1f76af7cd 100644
--- a/tools/transpiler/src/outputgeneration/DartParseTreeWriter.js
+++ b/tools/transpiler/src/outputgeneration/DartParseTreeWriter.js
@@ -323,8 +323,8 @@ export class DartParseTreeWriter extends JavaScriptParseTreeWriter {
     this.writeSpace_()
   }
 
-  visitNamedParamsExpression(tree) {
-    this.writeList_(tree.propertyNameAndValues, COMMA, false);
+  visitNamedParameterList(tree) {
+    this.writeList_(tree.parameterNameAndValues, COMMA, false);
   }
 
   toString() {
diff --git a/tools/transpiler/src/syntax/trees/ParseTreeType.js b/tools/transpiler/src/syntax/trees/ParseTreeType.js
index c0eaaf890c..9fe08500df 100644
--- a/tools/transpiler/src/syntax/trees/ParseTreeType.js
+++ b/tools/transpiler/src/syntax/trees/ParseTreeType.js
@@ -1,2 +1,4 @@
 export var CLASS_FIELD_DECLARATION = 'CLASS_FIELD_DECLARATION';
-export var PROPERTY_CONSTRUCTOR_ASSIGNMENT = 'PROPERTY_CONSTRUCTOR_ASSIGNMENT';
\ No newline at end of file
+export var PROPERTY_CONSTRUCTOR_ASSIGNMENT = 'PROPERTY_CONSTRUCTOR_ASSIGNMENT';
+export var NAMED_PARAMETER_LIST = 'NAMED_PARAMETER_LIST';
+export var OBJECT_PATTERN_BINDING_ELEMENT = 'OBJECT_PATTERN_BINDING_ELEMENT';
diff --git a/tools/transpiler/src/syntax/trees/ParseTrees.js b/tools/transpiler/src/syntax/trees/ParseTrees.js
index c3b5a52f23..8c32451029 100644
--- a/tools/transpiler/src/syntax/trees/ParseTrees.js
+++ b/tools/transpiler/src/syntax/trees/ParseTrees.js
@@ -4,9 +4,7 @@ import {PropertyMethodAssignment} from 'traceur/src/syntax/trees/ParseTrees';
 
 import * as ParseTreeType from './ParseTreeType';
 
-/**
- * Property declaration
- */
+// Class field declaration
 export class ClassFieldDeclaration extends ParseTree {
   constructor(location, lvalue, typeAnnotation, isFinal) {
     this.location = location;
@@ -30,9 +28,7 @@ export class ClassFieldDeclaration extends ParseTree {
 
 var CLASS_FIELD_DECLARATION = ParseTreeType.CLASS_FIELD_DECLARATION;
 
-/**
- * Class constructor
- */
+// Class constructor
 export class PropertyConstructorAssignment extends PropertyMethodAssignment {
   /**
    * @param {SourceRange} location
@@ -78,3 +74,73 @@ export class PropertyConstructorAssignment extends PropertyMethodAssignment {
 
 var PROPERTY_CONSTRUCTOR_ASSIGNMENT = ParseTreeType.PROPERTY_CONSTRUCTOR_ASSIGNMENT;
 
+// Named parameters
+export class NamedParameterList extends ParseTree {
+  /**
+   * @param {SourceRange} location
+   * @param {Array.<ParseTree>} parameterNameAndValues
+   */
+  constructor(location, parameterNameAndValues) {
+    this.location = location;
+    this.parameterNameAndValues = parameterNameAndValues;
+  }
+
+  /**
+   * @param {ParseTreeTransformer} transformer
+   */
+  transform(transformer) {
+    return transformer.transformNamedParameterList(this);
+  }
+
+  /**
+   * @param {ParseTreeVisitor} visitor
+   */
+  visit(visitor) {
+    visitor.visitNamedParameterList(this);
+  }
+
+  /**
+   * @type {ParseTreeType}
+   */
+  get type() {
+    return NAMED_PARAMETER_LIST;
+  }
+}
+
+var NAMED_PARAMETER_LIST = ParseTreeType.NAMED_PARAMETER_LIST;
+
+// Object pattern binding element
+export class ObjectPatternBindingElement extends ParseTree {
+  /**
+   * @param {SourceRange} location
+   * @param {BindingIdentifier|ObjectPattern|ArrayPattern} binding
+   * @param {ParseTree} initializer
+   */
+  constructor(location, binding, initializer) {
+    this.location = location;
+    this.binding = binding;
+    this.initializer = initializer;
+  }
+
+  /**
+   * @param {ParseTreeTransformer} transformer
+   */
+  transform(transformer) {
+    return transformer.transformObjectPatternBindingElement(this);
+  }
+
+  /**
+   * @param {ParseTreeVisitor} visitor
+   */
+  visit(visitor) {
+    visitor.visitObjectPatternBindingElement(this);
+  }
+
+  /**
+   * @type {ParseTreeType}
+   */
+  get type() {
+    return OBJECT_PATTERN_BINDING_ELEMENT;
+  }
+}
+var OBJECT_PATTERN_BINDING_ELEMENT = ParseTreeType.OBJECT_PATTERN_BINDING_ELEMENT;