Fix first part on liveness analysis of bug https://code.google.com/p/dart/issues/detail?id=9687: a …

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

Index: sdk/lib/_internal/compiler/implementation/ssa/codegen.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/ssa/codegen.dart	(revision 21192)
+++ sdk/lib/_internal/compiler/implementation/ssa/codegen.dart	(working copy)
@@ -337,11 +337,11 @@
     // Register return types to the backend.
     graph.exit.predecessors.forEach((HBasicBlock block) {
       HInstruction last = block.last;
-      assert(last is HGoto || last is HReturn);
+      assert(last is HGoto || last is HReturn || last is HThrow);
       if (last is HReturn) {
         backend.registerReturnType(
             work.element, last.inputs[0].instructionType);
-      } else {
+      } else if (last is HGoto) {
         backend.registerReturnType(work.element, HType.NULL);
       }
     });