Make guard_cid and nullable_cid half words.

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 6ccb225c4c062ab56c54a85bb3489c6077086dec..bb54355f149fe7875f439b6a811a32698a2c949b 100644
--- a/runtime/vm/assembler_ia32.cc
+++ b/runtime/vm/assembler_ia32.cc
@@ -268,6 +268,16 @@ void Assembler::movw(const Address& dst, Register src) {
 }
 
 
+void Assembler::movw(const Address& dst, const Immediate& imm) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitOperandSizeOverride();
+  EmitUint8(0xC7);
+  EmitOperand(0, dst);
+  EmitUint8(imm.value() & 0xFF);
+  EmitUint8((imm.value() >> 8) & 0xFF);
+}
+
+
 void Assembler::leal(Register dst, const Address& src) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitUint8(0x8D);
@@ -1417,6 +1427,24 @@ void Assembler::cmpl(const Address& address, const Immediate& imm) {
 }
 
 
+void Assembler::cmpw(Register reg, const Address& address) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitOperandSizeOverride();
+  EmitUint8(0x3B);
+  EmitOperand(reg, address);
+}
+
+
+void Assembler::cmpw(const Address& address, const Immediate& imm) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitOperandSizeOverride();
+  EmitUint8(0x81);
+  EmitOperand(7, address);
+  EmitUint8(imm.value() & 0xFF);
+  EmitUint8((imm.value() >> 8) & 0xFF);
+}
+
+
 void Assembler::cmpb(const Address& address, const Immediate& imm) {
   ASSERT(imm.is_int8());
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);