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

runtime/vm/assembler_mips.cc

Index: runtime/vm/assembler_mips.cc
diff --git a/runtime/vm/assembler_mips.cc b/runtime/vm/assembler_mips.cc
index 7660e2526dc73758a9b16ce24ab38937bc3b081e..846a817f73870f37c46760a9a280cbc48d2aac49 100644
--- a/runtime/vm/assembler_mips.cc
+++ b/runtime/vm/assembler_mips.cc
@@ -999,7 +999,7 @@ void Assembler::TryAllocate(const Class& cls,
     ASSERT(instance_size >= kHeapObjectTag);
     AddImmediate(instance_reg, -instance_size + kHeapObjectTag);
     NOT_IN_PRODUCT(UpdateAllocationStats(cls.id(), temp_reg, space));
-    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);
@@ -1049,7 +1049,7 @@ void Assembler::TryAllocateArray(intptr_t cid,
 
     // Initialize the tags.
     // instance: new object start as a tagged pointer.
-    uword tags = 0;
+    uint32_t tags = 0;
     tags = RawObject::ClassIdTag::update(cid, tags);
     tags = RawObject::SizeTag::update(instance_size, tags);
     LoadImmediate(temp1, tags);