VM: Reland Inline instance object hash code into object header on 64bit.

runtime/vm/assembler_ia32.cc

Index: runtime/vm/assembler_ia32.cc
diff --git a/runtime/vm/assembler_ia32.cc b/runtime/vm/assembler_ia32.cc
index 7ef2204d7759d3664926237b9e95f7b3fc33696a..a437c29cf829b1772eaf0c70a2b043b07ba20f12 100644
--- a/runtime/vm/assembler_ia32.cc
+++ b/runtime/vm/assembler_ia32.cc
@@ -2643,7 +2643,7 @@ void Assembler::TryAllocate(const Class& cls,
     NOT_IN_PRODUCT(UpdateAllocationStats(cls.id(), temp_reg, space));
     ASSERT(instance_size >= kHeapObjectTag);
     subl(instance_reg, Immediate(instance_size - kHeapObjectTag));
-    uword tags = 0;
+    uint32_t tags = 0;
     tags = RawObject::SizeTag::update(instance_size, tags);
     ASSERT(cls.id() != kIllegalCid);
     tags = RawObject::ClassIdTag::update(cls.id(), tags);
@@ -2690,7 +2690,7 @@ void Assembler::TryAllocateArray(intptr_t cid,
         UpdateAllocationStatsWithSize(cid, instance_size, temp_reg, space));
 
     // Initialize the tags.
-    uword tags = 0;
+    uint32_t tags = 0;
     tags = RawObject::ClassIdTag::update(cid, tags);
     tags = RawObject::SizeTag::update(instance_size, tags);
     movl(FieldAddress(instance, Object::tags_offset()), Immediate(tags));