Blocks that contain soft deopts have no side effects.

R=fschneider@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9188005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10938 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen.cc

@@ -1485,6 +1485,11 @@ void HGlobalValueNumberer::ComputeBlockSideEffects() {
     GVNFlagSet side_effects;
     while (instr != NULL) {
       side_effects.Add(instr->ChangesFlags());
+      if (instr->IsSoftDeoptimize()) {
+        block_side_effects_[id].RemoveAll();
+        side_effects.RemoveAll();
+        break;
+      }
       instr = instr->next();
     }
     block_side_effects_[id].Add(side_effects);