Reduce generated ARM code size for ReturnInstr by one instruction

runtime/vm/assembler_arm.cc

 // 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.
 
 #include "vm/globals.h"  // NOLINT
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 3204 matching lines @@
 
   AddImmediate(SP, -extra_size);
 }
 
 
 void Assembler::LeaveDartFrame(RestorePP restore_pp) {
   if (restore_pp == kRestoreCallerPP) {
     ldr(PP, Address(FP, kSavedCallerPpSlotFromFp * kWordSize));
     set_constant_pool_allowed(false);
   }
-  Drop(2);  // Drop saved PP, PC marker.
+
+  // This will implicitly drop saved PP, PC marker due to restoring SP from FP
+  // first.
   LeaveFrame((1 << FP) | (1 << LR));
 }
 
 
 void Assembler::EnterStubFrame() {
   EnterDartFrame(0);
 }
 
 
 void Assembler::LeaveStubFrame() {
@@ skipping 272 matching lines @@
 
 
 const char* Assembler::FpuRegisterName(FpuRegister reg) {
   ASSERT((0 <= reg) && (reg < kNumberOfFpuRegisters));
   return fpu_reg_names[reg];
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM