X64: Checked and slightly modified Object layouts to be compatible with 64-bit pointers.

src/log.cc

Index: src/log.cc
diff --git a/src/log.cc b/src/log.cc
index 08f68fd698979aad8d191585ea60d683c0f21995..79cbfcf88f8a32a781690da5bdb499974531afbd 100644
--- a/src/log.cc
+++ b/src/log.cc
@@ -1266,7 +1266,7 @@ static const char* StateToString(StateTag state) {
 VMState::VMState(StateTag state) {
 #if !defined(ENABLE_HEAP_PROTECTION)
   // When not protecting the heap, there is no difference between
-  // EXTERNAL and OTHER.  As an optimizatin in that case, we will not
+  // EXTERNAL and OTHER.  As an optimization in that case, we will not
   // perform EXTERNAL->OTHER transitions through the API.  We thus
   // compress the two states into one.
   if (state == EXTERNAL) state = OTHER;