Cache current thread in a reserved register and use it in LoadIsolate

runtime/vm/assembler_ia32.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_ASSEMBLER_IA32_H_
 #define VM_ASSEMBLER_IA32_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_ia32.h directly; use assembler.h instead.
 #endif
@@ skipping 830 matching lines @@
   //   ret PC
   //   saved EBP
   //   0 (used to indicate frame is a stub frame)
   //   .....
   // This code sets this up with the sequence:
   //   pushl ebp
   //   movl ebp, esp
   //   pushl immediate(0)
   //   .....
   void EnterStubFrame();
+  static const intptr_t kEnterStubFramePushedWords = 2;
 
   // Instruction pattern from entrypoint is used in dart frame prologs
   // to set up the frame and save a PC which can be used to figure out the
   // RawInstruction object corresponding to the code running in the frame.
   // entrypoint:
   //   pushl ebp          (size is 1 byte)
   //   movl ebp, esp      (size is 2 bytes)
   //   call L             (size is 5 bytes)
   //   L:
   static const intptr_t kEntryPointToPcMarkerOffset = 8;
@@ skipping 161 matching lines @@
 }
 
 
 inline void Assembler::EmitOperandSizeOverride() {
   EmitUint8(0x66);
 }
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_IA32_H_