Implement CHA through type mask and TypedSelector in the simple type inferrer.

sdk/lib/_internal/compiler/implementation/compiler.dart

Index: sdk/lib/_internal/compiler/implementation/compiler.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/compiler.dart	(revision 19615)
+++ sdk/lib/_internal/compiler/implementation/compiler.dart	(working copy)
@@ -155,6 +155,16 @@
   bool isNullImplementation(ClassElement cls) {
     return cls == compiler.nullClass;
   }
+  ClassElement get intImplementation => compiler.intClass;
+  ClassElement get doubleImplementation => compiler.doubleClass;
+  ClassElement get numImplementation => compiler.numClass;
+  ClassElement get stringImplementation => compiler.stringClass;
+  ClassElement get listImplementation => compiler.listClass;
+  ClassElement get mapImplementation => compiler.mapClass;
+  ClassElement get functionImplementation => compiler.functionClass;
+  ClassElement get typeImplementation => compiler.typeClass;
+  ClassElement get boolImplementation => compiler.boolClass;
+  ClassElement get nullImplementation => compiler.nullClass;
 }
 
 /**
@@ -265,7 +275,6 @@
   ClassElement listClass;
   ClassElement typeClass;
   ClassElement mapClass;
-  ClassElement mapLiteralClass;
   ClassElement jsInvocationMirrorClass;
   /// Document class from dart:mirrors.
   ClassElement documentClass;
@@ -560,8 +569,6 @@
     listClass = lookupCoreClass('List');
     typeClass = lookupCoreClass('Type');
     mapClass = lookupCoreClass('Map');
-    // TODO: find a proper way to get to the implementation class.
-    mapLiteralClass = lookupCoreClass('LinkedHashMap');
     if (!missingCoreClasses.isEmpty) {
       internalErrorOnElement(coreLibrary,
           'dart:core library does not contain required classes: '