Explicitly Disallow heap allocation when wasm memory references are updated

src/runtime/runtime-wasm.cc

Index: src/runtime/runtime-wasm.cc
diff --git a/src/runtime/runtime-wasm.cc b/src/runtime/runtime-wasm.cc
index 75e2a76b8b2965527828af6fee0c07e4be38f1f8..0817ff5854fc9d3815fbaf22fe01e12ba4e4fdd5 100644
--- a/src/runtime/runtime-wasm.cc
+++ b/src/runtime/runtime-wasm.cc
@@ -30,7 +30,7 @@ RUNTIME_FUNCTION(Runtime_WasmGrowMemory) {
   Code* code = isolate->inner_pointer_to_code_cache()->GetCacheEntry(pc)->code;

[ahaas, 2016/06/29 07:13:31]

Use also "the DisallowHeapAllocation no_allocation;" scope here for the lifetime
of code, deopt_data, and obj below. These are pointers into the heap, and we
have to make sure that they are valid as long as they exist, i.e. that the GC
does not move the targeted objects away. Since the scope should not be the whole
function, you can create a sub-scope with { and }.

[gdeepti, 2016/06/29 23:38:38]

Thanks for clarifying that, used "DisallowHeapAllocation no_allocation;" for the
lifetime of code, deopt_data, and changed obj to a handle. 

   FixedArray* deopt_data = code->deoptimization_data();
   DCHECK(deopt_data->length() == 2);
-  JSObject* module_object = JSObject::cast(deopt_data->get(0));
+  Handle<JSObject> module_object(JSObject::cast(deopt_data->get(0)));
   RUNTIME_ASSERT(!module_object->IsNull(isolate));
 
   Address old_mem_start, new_mem_start;