Some string optimizations:

src/mips/codegen-mips.cc

Index: src/mips/codegen-mips.cc
diff --git a/src/mips/codegen-mips.cc b/src/mips/codegen-mips.cc
index 5a27c2864856a806dde44a67334c54ef83fe43a5..2de45f67f0ac4e7d623e1ad4975a6ded30325d8e 100644
--- a/src/mips/codegen-mips.cc
+++ b/src/mips/codegen-mips.cc
@@ -305,6 +305,11 @@ void CodeGenerator::GenerateIsArray(ZoneList<Expression*>* args) {
 }
 
 
+void CodeGenerator::GenerateIsRegExp(ZoneList<Expression*>* args) {
+  UNIMPLEMENTED_MIPS();
+}
+
+
 void CodeGenerator::GenerateIsConstructCall(ZoneList<Expression*>* args) {
   UNIMPLEMENTED_MIPS();
 }
@@ -365,6 +370,11 @@ void CodeGenerator::GenerateRegExpExec(ZoneList<Expression*>* args) {
 }
 
 
+void CodeGenerator::GenerateNumberToString(ZoneList<Expression*>* args) {
+  UNIMPLEMENTED_MIPS();
+}
+
+
 void CodeGenerator::VisitCallRuntime(CallRuntime* node) {
   UNIMPLEMENTED_MIPS();
 }
@@ -498,4 +508,3 @@ int CompareStub::MinorKey() {
 #undef __
 
 } }  // namespace v8::internal
-