Implement try/catch without finally, and without type checks.

frog/leg/ssa/optimize.dart

Index: frog/leg/ssa/optimize.dart
===================================================================
--- frog/leg/ssa/optimize.dart	(revision 4024)
+++ frog/leg/ssa/optimize.dart	(working copy)
@@ -11,9 +11,11 @@
       if (!work.isBailoutVersion()) {
         // TODO(ngeoffray): We should be more fine-grained and still
         // allow type propagation of instructions we know the type.
-        new SsaTypePropagator(compiler).visitGraph(graph);
-        new SsaTypeGuardBuilder(compiler).visitGraph(graph);
-        new SsaCheckInserter(compiler).visitGraph(graph);
+        if (work.allowSpeculativeOptimization) {
+          new SsaTypePropagator(compiler).visitGraph(graph);
+          new SsaTypeGuardBuilder(compiler).visitGraph(graph);
+          new SsaCheckInserter(compiler).visitGraph(graph);
+        }
         new SsaConstantFolder(compiler).visitGraph(graph);
         new SsaRedundantPhiEliminator().visitGraph(graph);
         new SsaDeadPhiEliminator().visitGraph(graph);