Expand the class id to 32 bits and size field to 16 bits on 64-bit platforms.

runtime/vm/disassembler_ia32.cc

Index: runtime/vm/disassembler_ia32.cc
diff --git a/runtime/vm/disassembler_ia32.cc b/runtime/vm/disassembler_ia32.cc
index c3b1d562692b9c7c789d7075189af96a9d2539e6..c63057b80987ea1f5ebf98936fe5d7353b5d0f7c 100644
--- a/runtime/vm/disassembler_ia32.cc
+++ b/runtime/vm/disassembler_ia32.cc
@@ -729,11 +729,6 @@ int X86Decoder::PrintImmediateOp(uint8_t* data, bool size_override) {
     default: UNIMPLEMENTED();
   }
   Print(mnem);
-  if (size_override) {
-    Print("_w");
-  } else if (sign_extension_bit) {
-    Print("_b");
-  }
   Print(" ");
   int count = PrintRightOperand(data+1);
   Print(",");