Annotate V8 for MemorySanitizer.

src/frames-inl.h

Index: src/frames-inl.h
===================================================================
--- src/frames-inl.h	(revision 17104)
+++ src/frames-inl.h	(working copy)
@@ -30,6 +30,7 @@
 
 #include "frames.h"
 #include "isolate.h"
+#include "msan.h"
 #include "v8memory.h"
 
 #if V8_TARGET_ARCH_IA32
@@ -137,13 +138,16 @@
 
 
 inline Address* StackFrame::ResolveReturnAddressLocation(Address* pc_address) {
+  Address *a;
   if (return_address_location_resolver_ == NULL) {
-    return pc_address;
+    a = pc_address;
   } else {
-    return reinterpret_cast<Address*>(
+    a = reinterpret_cast<Address*>(
         return_address_location_resolver_(
             reinterpret_cast<uintptr_t>(pc_address)));
   }
+  MSAN_MEMORY_IS_INITIALIZED(a, sizeof(*a));
+  return a;
 }