Move the handling of operator[] into the new interceptors.

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

Index: sdk/lib/_internal/compiler/implementation/ssa/optimize.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/ssa/optimize.dart	(revision 15954)
+++ sdk/lib/_internal/compiler/implementation/ssa/optimize.dart	(working copy)
@@ -206,8 +206,7 @@
     return node;
   }
 
-  HInstruction handleInterceptorCall(HInvokeDynamic node) {
-    if (node is !HInvokeDynamicMethod) return null;
+  HInstruction handleInterceptorCall(HInvokeDynamicMethod node) {
     HInstruction input = node.inputs[1];
     if (input.isString(types)
         && node.selector.name == const SourceString('toString')) {
@@ -229,6 +228,11 @@
     }
 
     Selector selector = node.selector;
+
+    if (node.isIndexOperatorOnIndexablePrimitive(types)) {
+      return new HIndex(node.inputs[1], node.inputs[2]);
+    }
+
     SourceString selectorName = selector.name;
     Element target;
     if (input.isExtendableArray(types)) {
@@ -277,7 +281,7 @@
     return node;
   }
 
-  HInstruction visitInvokeDynamic(HInvokeDynamic node) {
+  HInstruction visitInvokeDynamicMethod(HInvokeDynamicMethod node) {
     if (node.isInterceptorCall) return handleInterceptorCall(node);
     HType receiverType = types[node.receiver];
     if (receiverType.isExact()) {
@@ -304,7 +308,7 @@
    * [HInvokeDynamic] because we know the receiver is not a JS
    * primitive object.
    */
-  HInstruction fromPrimitiveInstructionToDynamicInvocation(HInvokeStatic node,
+  HInstruction fromPrimitiveInstructionToDynamicInvocation(HInstruction node,
                                                            Selector selector) {
     HBoundedType type = types[node.inputs[1]];
     HInvokeDynamicMethod result = new HInvokeDynamicMethod(
@@ -331,15 +335,6 @@
     return node;
   }
 
-
-  HInstruction visitIndex(HIndex node) {
-    if (!node.receiver.canBePrimitive(types)) {
-      Selector selector = new Selector.index();
-      return fromPrimitiveInstructionToDynamicInvocation(node, selector);
-    }
-    return node;
-  }
-
   HInstruction visitIndexAssign(HIndexAssign node) {
     if (!node.receiver.canBePrimitive(types)) {
       Selector selector = new Selector.indexSet();
@@ -803,7 +798,6 @@
   }
 
   void visitIndex(HIndex node) {
-    if (!node.receiver.isIndexablePrimitive(types)) return;
     if (boundsChecked.contains(node)) return;
     HInstruction index = node.index;
     if (!node.index.isInteger(types)) {
@@ -811,7 +805,6 @@
     }
     index = insertBoundsCheck(node, node.receiver, index);
     node.changeUse(node.index, index);
-    assert(node.isBuiltin(types));
   }
 
   void visitIndexAssign(HIndexAssign node) {