Start new design for interceptors and implement String.charCodeAt with it.

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

Index: sdk/lib/_internal/compiler/implementation/ssa/variable_allocator.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/ssa/variable_allocator.dart	(revision 14840)
+++ sdk/lib/_internal/compiler/implementation/ssa/variable_allocator.dart	(working copy)
@@ -441,13 +441,17 @@
  */
 class VariableNamer {
   final VariableNames names;
+  final Compiler compiler;
   final Set<String> usedNames;
   final Map<Element, String> parameterNames;
   final List<String> freeTemporaryNames;
   int temporaryIndex = 0;
   static final RegExp regexp = new RegExp('t[0-9]+');
 
-  VariableNamer(LiveEnvironment environment, this.names, this.parameterNames)
+  VariableNamer(LiveEnvironment environment,
+                this.names,
+                this.parameterNames,
+                this.compiler)
     : usedNames = new Set<String>(),
       freeTemporaryNames = new List<String>() {
     // [VariableNames.swapTemp] is used when there is a cycle in a copy handler.
@@ -512,11 +516,23 @@
       if (name != null) return addAllocatedName(instruction, name);
     }
 
-    // The dom/html libraries have inline JS code that reference	
-    // parameter names directly. Long-term such code will be rejected.
-    // Now, just don't mangle the parameter name.
-    if (instruction is HParameterValue
+    if (instruction is HThis) {
+      name = "this";
+      if (instruction.sourceElement != null) {
+        Element cls = instruction.sourceElement.getEnclosingClass();
+        // Change the name of [:this:] in a method of a foreign class
+        // to use the first parameter of the method, which is the
+        // actual receiver.
+        JavaScriptBackend backend = compiler.backend;
+        if (backend.isInterceptorClass(cls)) {
+          name = "primitive";
+        }
+      }
+    } else if (instruction is HParameterValue
         && instruction.sourceElement.enclosingElement.isNative()) {
+      // The dom/html libraries have inline JS code that reference	
+      // parameter names directly. Long-term such code will be rejected.
+      // Now, just don't mangle the parameter name.
       name = instruction.sourceElement.name.slowToString();
     } else if (instruction.sourceElement != null) {
       name = allocateWithHint(instruction.sourceElement.name.slowToString());
@@ -531,12 +547,11 @@
         name = allocateTemporary();
       }
     }
-
     return addAllocatedName(instruction, name);
   }
 
   String addAllocatedName(HInstruction instruction, String name) {
-    if (instruction is HParameterValue) {
+    if (instruction is HParameterValue && name != 'this') {
       parameterNames[instruction.sourceElement] = name;
     }
     usedNames.add(name);
@@ -599,7 +614,7 @@
 
   void visitBasicBlock(HBasicBlock block) {
     VariableNamer namer = new VariableNamer(
-        liveInstructions[block], names, parameterNames);
+        liveInstructions[block], names, parameterNames, compiler);
 
     block.forEachPhi((HPhi phi) {
       handlePhi(phi, namer);
@@ -618,7 +633,7 @@
     // TODO(ngeoffray): locals/parameters are being generated at use site,
     // but we need a name for them. We should probably not make
     // them generate at use site to make things simpler.
-    if (instruction is HLocalValue && instruction is !HThis) return true;
+    if (instruction is HLocalValue) return true;
     if (instruction.usedBy.isEmpty) return false;
     if (generateAtUseSite.contains(instruction)) return false;
     // A [HCheck] instruction that has control flow needs a name only if its