Optimize the typeof operator.

src/mips/interface-descriptors-mips.cc

Index: src/mips/interface-descriptors-mips.cc
diff --git a/src/mips/interface-descriptors-mips.cc b/src/mips/interface-descriptors-mips.cc
index 96bb2af4d0e01782999b00ccb3d3ae59f9a27875..01db51672a5fcf74e144301de7b5ba70e8f7f400 100644
--- a/src/mips/interface-descriptors-mips.cc
+++ b/src/mips/interface-descriptors-mips.cc
@@ -83,6 +83,12 @@ void NumberToStringDescriptor::Initialize(CallInterfaceDescriptorData* data) {
 }
 
 
+void TypeofDescriptor::Initialize(CallInterfaceDescriptorData* data) {
+  Register registers[] = {cp, a3};
+  data->Initialize(arraysize(registers), registers, NULL);
+}
+
+
 void FastCloneShallowArrayDescriptor::Initialize(
     CallInterfaceDescriptorData* data) {
   Register registers[] = {cp, a3, a2, a1};