fix(ngcc): correctly read static properties for aliased classes (#32619)

In ESM2015 bundles, a class with decorators may be emitted as follows:

```javascript
var MyClass_1;
let MyClass = MyClass_1 = class MyClass {};
MyClass.decorators = [/* here be decorators */];
```

Such a class has two declarations: the publicly visible `let MyClass`
and the implementation `class MyClass {}` node. In #32539 a refactoring
took place to handle such classes more consistently, however the logic
to find static properties was mistakenly kept identical to its broken
state before the refactor, by looking for static properties on the
implementation symbol (the one for `class MyClass {}`) whereas the
static properties need to be obtained from the symbol corresponding with
the `let MyClass` declaration, as that is where the `decorators`
property is assigned to in the example above.

This commit fixes the behavior by looking for static properties on the
public declaration symbol. This fixes an issue where decorators were not
found for classes that do in fact have decorators, therefore preventing
the classes from being compiled for Ivy.

Fixes #31791

PR Close #32619

packages/compiler-cli/ngcc/src/host/esm2015_host.ts

@@ -638,7 +638,7 @@ export class Esm2015ReflectionHost extends TypeScriptReflectionHost implements N
    */
   protected getStaticProperty(symbol: NgccClassSymbol, propertyName: ts.__String): ts.Symbol
       |undefined {
-    return symbol.implementation.exports && symbol.implementation.exports.get(propertyName);
+    return symbol.declaration.exports && symbol.declaration.exports.get(propertyName);
   }
 
   /**

packages/compiler-cli/ngcc/test/host/esm2015_host_spec.ts

@@ -132,9 +132,13 @@ runInEachFileSystem(() => {
       CLASS_EXPRESSION_FILE = {
         name: _('/class_expression.js'),
         contents: `
+    import {Directive} from '@angular/core';
     var AliasedClass_1;
     let EmptyClass = class EmptyClass {};
     let AliasedClass = AliasedClass_1 = class AliasedClass {}
+    AliasedClass.decorators = [
+      { type: Directive, args: [{ selector: '[someDirective]' },] }
+    ];
     let usageOfAliasedClass = AliasedClass_1;
   `,
       };
@@ -708,6 +712,25 @@ runInEachFileSystem(() => {
         ]);
       });
 
+      it('should find the decorators on an aliased class', () => {
+        loadTestFiles([CLASS_EXPRESSION_FILE]);
+        const {program} = makeTestBundleProgram(CLASS_EXPRESSION_FILE.name);
+        const host = new Esm2015ReflectionHost(new MockLogger(), false, program.getTypeChecker());
+        const classNode = getDeclaration(
+            program, CLASS_EXPRESSION_FILE.name, 'AliasedClass', isNamedVariableDeclaration);
+        const decorators = host.getDecoratorsOfDeclaration(classNode) !;
+
+        expect(decorators).toBeDefined();
+        expect(decorators.length).toEqual(1);
+
+        const decorator = decorators[0];
+        expect(decorator.name).toEqual('Directive');
+        expect(decorator.import).toEqual({name: 'Directive', from: '@angular/core'});
+        expect(decorator.args !.map(arg => arg.getText())).toEqual([
+          '{ selector: \'[someDirective]\' }',
+        ]);
+      });
+
       it('should return null if the symbol is not a class', () => {
         loadTestFiles([FOO_FUNCTION_FILE]);
         const {program} = makeTestBundleProgram(FOO_FUNCTION_FILE.name);