ARM: Add optimization for constant RHS in DoMulI.

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
===================================================================
--- src/arm/code-stubs-arm.cc	(revision 8145)
+++ src/arm/code-stubs-arm.cc	(working copy)
@@ -2666,9 +2666,11 @@
           // DIV just falls through to allocating a heap number.
         }
 
+        __ bind(&return_heap_number);
+        // Return a heap number, or fall through to type transition or runtime
+        // call if we can't.
         if (result_type_ >= (op_ == Token::DIV) ? BinaryOpIC::HEAP_NUMBER
                                                 : BinaryOpIC::INT32) {
-          __ bind(&return_heap_number);
           // We are using vfp registers so r5 is available.
           heap_number_result = r5;
           GenerateHeapResultAllocation(masm,
@@ -2842,7 +2844,11 @@
       UNREACHABLE();
   }
 
-  if (transition.is_linked()) {
+  // We never expect DIV to yield an integer result, so we always generate
+  // type transition code for DIV operations expecting an integer result: the
+  // code will fall through to this type transition.
+  if (transition.is_linked() ||
+      ((op_ == Token::DIV) && (result_type_ <= BinaryOpIC::INT32))) {
     __ bind(&transition);
     GenerateTypeTransition(masm);
   }