chore: remove deprecated liveExample mixins (#2670)

`+liveExample` mixins were replaced by `<live-example>` directives a
while ago. This cleanup fixes link issues to the plunker under ng2.io.

public/docs/dart/latest/_util-fns.jade

@@ -29,20 +29,6 @@ include ../../../_includes/_util-fns
 - var _moduleVsRootComp = 'root component'
 - var _platformBrowserDynamicVsBootStrap = 'bootstrap'
 
-//- Deprecated
-mixin liveExampleLink(linkText, exampleUrlPartName)
-  - var text = linkText || 'live example';
-  - var ex = exampleUrlPartName || getExampleName();
-  - var href = 'http://angular-examples.github.io/' + ex;
-  a(href='#{href}' target="_blank")= text
-
-//- Deprecated
-mixin liveExampleLink2(linkText, exampleUrlPartName)
-  - var srcText = attributes.srcText || 'view source';
-  - var ex = exampleUrlPartName || attributes.example || getExampleName();
-  - var href = 'http://github.com/angular-examples/' + ex;
-  span #[+liveExampleLink(linkText, ex)] (#[a(href='#{href}' target="_blank") #{srcText}])
-
 - var adjustTsExamplePathForDart = function(_path) {
 -   if(!_path) return _path;
 -   var path = _path.trim();

public/docs/ts/_cache/guide/architecture.jade

@@ -41,7 +41,7 @@ figure
   Learn these, and we're on our way.
 
 .l-sub-section
-  p The code referenced in this chapter is available as a #[+liveExampleLink2()].
+  p The code referenced in this chapter is available as a <live-example></live-example>.
 
 .l-main-section
 :marked

public/docs/ts/latest/_util-fns.jade

@@ -3,15 +3,3 @@ include ../../../_includes/_util-fns
 //- See the _util-fns file included above for a description of the use of these variables.
 - var _docsFor = 'ts';
 //- Other values match the defaults.
-
-//- Deprecated
-mixin liveExampleLink(linkText, exampleUrlPartName)
-  - var text = linkText || 'live example';
-  - var ex = exampleUrlPartName || getExampleName();
-  - var href = '/resources/live-examples/' + ex + '/ts/plnkr.html';
-  a(href='#{href}' target="_blank")= text
-
-//- Deprecated
-mixin liveExampleLink2(linkText, exampleUrlPartName)
-  //- In Dart this gives 2 links: to the demo and to the source.
-  +liveExampleLink(linkText, exampleUrlPartName)

public/docs/ts/latest/guide/architecture.jade

@@ -41,7 +41,7 @@ figure
   Learn these building blocks, and you're on your way.
 
 .l-sub-section
-  p The code referenced on this page is available as a #[+liveExampleLink2()].
+  p The code referenced on this page is available as a <live-example></live-example>.
 
 .l-main-section
 :marked