Use JavaScript runtime semantics when constant folding.

lib/compiler/implementation/ssa/optimize.dart

Index: lib/compiler/implementation/ssa/optimize.dart
diff --git a/lib/compiler/implementation/ssa/optimize.dart b/lib/compiler/implementation/ssa/optimize.dart
index 4faa8e9e2e4ae016ee5352b71ae07b34f8c7f2fd..736454c6883ac5bd1ba0b37a03be76f8886dd3cd 100644
--- a/lib/compiler/implementation/ssa/optimize.dart
+++ b/lib/compiler/implementation/ssa/optimize.dart
@@ -23,15 +23,17 @@ class SsaOptimizerTask extends CompilerTask {
   }
 
   void optimize(WorkItem work, HGraph graph) {
+    FoldingOperations foldingOperations =
+        compiler.constantHandler.foldingOperations;
     measure(() {
       List<OptimizationPhase> phases = <OptimizationPhase>[
           // Run trivial constant folding first to optimize
           // some patterns useful for type conversion.
-          new SsaConstantFolder(backend, work),
+          new SsaConstantFolder(foldingOperations, backend, work),
           new SsaTypeConversionInserter(compiler),
           new SsaTypePropagator(compiler),
           new SsaCheckInserter(backend),
-          new SsaConstantFolder(backend, work),
+          new SsaConstantFolder(foldingOperations, backend, work),
           new SsaRedundantPhiEliminator(),
           new SsaDeadPhiEliminator(),
           new SsaGlobalValueNumberer(compiler),
@@ -93,10 +95,11 @@ class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase {
   final String name = "SsaConstantFolder";
   final JavaScriptBackend backend;
   final WorkItem work;
+  final FoldingOperations foldingOperations;
   HGraph graph;
   Compiler get compiler() => backend.compiler;
 
-  SsaConstantFolder(this.backend, this.work);
+  SsaConstantFolder(this.foldingOperations, this.backend, this.work);
 
   void visitGraph(HGraph visitee) {
     graph = visitee;
@@ -165,7 +168,7 @@ class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase {
   HInstruction visitInvokeUnary(HInvokeUnary node) {
     HInstruction operand = node.operand;
     if (operand is HConstant) {
-      UnaryOperation operation = node.operation;
+      UnaryOperation operation = node.operation(foldingOperations);
       HConstant receiver = operand;
       Constant folded = operation.fold(receiver.constant);
       if (folded !== null) return graph.addConstant(folded);
@@ -319,8 +322,8 @@ class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase {
   HInstruction visitInvokeBinary(HInvokeBinary node) {
     HInstruction left = node.left;
     HInstruction right = node.right;
+    BinaryOperation operation = node.operation(foldingOperations);
     if (left is HConstant && right is HConstant) {
-      BinaryOperation operation = node.operation;
       HConstant op1 = left;
       HConstant op2 = right;
       Constant folded = operation.fold(op1.constant, op2.constant);
@@ -328,10 +331,10 @@ class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase {
     }
 
     if (!left.canBePrimitive()
-        && node.operation.isUserDefinable()
+        && operation.isUserDefinable()
         // The equals operation is being optimized in visitEquals.
-        && node.operation !== const EqualsOperation()) {
-      Selector selector = new Selector.binaryOperator(node.operation.name);
+        && node is! HEquals) {
+      Selector selector = new Selector.binaryOperator(operation.name);
       return fromInterceptorToDynamicInvocation(node, selector);
     }
     return node;