Re-assign registers on ARM so PP and CODE_REG are below R7 (FP on iOS).

runtime/vm/runtime_entry_arm.cc

 // Copyright (c) 2011, 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"
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/runtime_entry.h"
 
 #include "vm/assembler.h"
@@ skipping 24 matching lines @@
   entry =
       Simulator::RedirectExternalReference(entry, call_kind, argument_count());
 #endif
   return entry;
 }
 
 
 // Generate code to call into the stub which will call the runtime
 // function. Input for the stub is as follows:
 //   SP : points to the arguments and return value array.
-//   R5 : address of the runtime function to call.
+//   R9 : address of the runtime function to call.
 //   R4 : number of arguments to the call.
 void RuntimeEntry::Call(Assembler* assembler, intptr_t argument_count) const {
   if (is_leaf()) {
     ASSERT(argument_count == this->argument_count());
     __ BranchLinkOffset(THR, Thread::OffsetFromThread(this));
   } else {
     // Argument count is not checked here, but in the runtime entry for a more
     // informative error message.
-    __ LoadFromOffset(kWord, R5, THR, Thread::OffsetFromThread(this));
+    __ LoadFromOffset(kWord, R9, THR, Thread::OffsetFromThread(this));
     __ LoadImmediate(R4, argument_count);
     __ BranchLink(*StubCode::CallToRuntime_entry(), kNotPatchable);
   }
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM