Remove scratch register requirement from LoadInstanceDescriptors on arm and mips.

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 1209372ef17f53e03de7efc944804d6e4614c841..89f3b034cead49b9e784714e1032af62a8013591 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -1137,7 +1137,7 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ cmp(r1, Operand(Smi::FromInt(0)));
   __ b(eq, &no_descriptors);
 
-  __ LoadInstanceDescriptors(r0, r2, r4);
+  __ LoadInstanceDescriptors(r0, r2);
   __ ldr(r2, FieldMemOperand(r2, DescriptorArray::kEnumCacheOffset));
   __ ldr(r2, FieldMemOperand(r2, DescriptorArray::kEnumCacheBridgeCacheOffset));
 
@@ -2683,7 +2683,7 @@ void FullCodeGenerator::EmitIsStringWrapperSafeForDefaultValueOf(
   __ cmp(r3, Operand(0));
   __ b(eq, &done);
 
-  __ LoadInstanceDescriptors(r1, r4, r2);
+  __ LoadInstanceDescriptors(r1, r4);
   // r4: descriptor array.
   // r3: valid entries in the descriptor array.
   STATIC_ASSERT(kSmiTag == 0);