Implement leaf runtime call stub on ARM and corresponding call redirection

runtime/vm/assembler_arm.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_ARM_H_
 #define VM_ASSEMBLER_ARM_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_arm.h directly; use assembler.h instead.
 #endif
@@ skipping 500 matching lines @@
   void blx(Register rm, Condition cond = AL);
 
   // Move to ARM core register from Coprocessor.
   void mrc(Register rd, int32_t coproc, int32_t opc1,
            int32_t crn, int32_t crm, int32_t opc2, Condition cond = AL);
 
   // Macros.
   // Branch to an entry address. Call sequence is never patched.
   void Branch(const ExternalLabel* label, Condition cond = AL);
 
+  // Branch to an entry address. Call sequence can be patched or even replaced.
+  void BranchPatchable(const ExternalLabel* label);
+
   // Branch and link to an entry address. Call sequence is never patched.
   void BranchLink(const ExternalLabel* label);
 
   // Branch and link to an entry address. Call sequence can be patched.
   void BranchLinkPatchable(const ExternalLabel* label);
 
   // Branch and link to entry after storing return address at ad.
   // Call sequence is never patched.
   void BranchLinkStore(const ExternalLabel* label, Address ad);
 
@@ skipping 238 matching lines @@
     return *reg1 - *reg2;
   }
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(Assembler);
 };
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_ARM_H_