Support non-speculative type propagation.

frog/leg/ssa/optimize.dart

Index: frog/leg/ssa/optimize.dart
===================================================================
--- frog/leg/ssa/optimize.dart	(revision 5905)
+++ frog/leg/ssa/optimize.dart	(working copy)
@@ -21,6 +21,8 @@
   void optimize(WorkItem work, HGraph graph) {
     measure(() {
       List<OptimizationPhase> phases = <OptimizationPhase>[
+          new SsaTypePropagator(compiler, false),
+          new SsaCheckInserter(compiler),
           new SsaConstantFolder(compiler),
           new SsaRedundantPhiEliminator(),
           new SsaDeadPhiEliminator(),
@@ -38,7 +40,7 @@
       // types non-speculatively. For example, it propagates the type
       // array for a call to the List constructor.
       List<OptimizationPhase> phases = <OptimizationPhase>[
-          new SsaTypePropagator(compiler),
+          new SsaTypePropagator(compiler, true),
           new SsaTypeGuardBuilder(compiler, work),
           new SsaCheckInserter(compiler)];
       runPhases(graph, phases);
@@ -99,7 +101,7 @@
         // must update the type of this instruction manually. Later
         // phases can then optimize this instruction based on its
         // type.
-        replacement.updateType();
+        replacement.type = instruction.type;
       }
       instruction = next;
     }
@@ -297,6 +299,7 @@
 
   void visitIndex(HIndex node) {
     if (!node.builtin) return;
+    if (node.index is HBoundsCheck) return;
     HInstruction index = insertIntegerCheck(node, node.index);
     index = insertBoundsCheck(node, node.receiver, index);
     HIndex newInstruction = new HIndex(node.target, node.receiver, index);
@@ -307,6 +310,7 @@
 
   void visitIndexAssign(HIndexAssign node) {
     if (!node.builtin) return;
+    if (node.index is HBoundsCheck) return;
     HInstruction index = insertIntegerCheck(node, node.index);
     index = insertBoundsCheck(node, node.receiver, index);
     HIndexAssign newInstruction =