Get rid of HStringLength.

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index d7d12411d40c8b5ece5423709696a674c7ea67fc..be5809dd8de2788f113ca462fe809709672f1544 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -4596,13 +4596,6 @@ void LCodeGen::DoDeferredStringCharFromCode(LStringCharFromCode* instr) {
 }
 
 
-void LCodeGen::DoStringLength(LStringLength* instr) {
-  Register string = ToRegister(instr->string());
-  Register result = ToRegister(instr->result());
-  __ lw(result, FieldMemOperand(string, String::kLengthOffset));
-}
-
-
 void LCodeGen::DoInteger32ToDouble(LInteger32ToDouble* instr) {
   LOperand* input = instr->value();
   ASSERT(input->IsRegister() || input->IsStackSlot());