Add mips64 port.

src/mips64/lithium-codegen-mips64.h

Index: src/mips64/lithium-codegen-mips64.h
diff --git a/src/mips/lithium-codegen-mips.h b/src/mips64/lithium-codegen-mips64.h
similarity index 98%
copy from src/mips/lithium-codegen-mips.h
copy to src/mips64/lithium-codegen-mips64.h
index df0da84889102d4a434b4adb376bacf4cc1a7047..b2f8497b86d0a93242735272953c420aaabb5403 100644
--- a/src/mips/lithium-codegen-mips.h
+++ b/src/mips64/lithium-codegen-mips64.h
@@ -7,8 +7,8 @@
 
 #include "src/deoptimizer.h"
 #include "src/lithium-codegen.h"
-#include "src/mips/lithium-gap-resolver-mips.h"
-#include "src/mips/lithium-mips.h"
+#include "src/mips64/lithium-gap-resolver-mips64.h"
+#include "src/mips64/lithium-mips64.h"
 #include "src/safepoint-table.h"
 #include "src/scopes.h"
 #include "src/utils.h"
@@ -76,7 +76,8 @@ class LCodeGen: public LCodeGenBase {
   DoubleRegister EmitLoadDoubleRegister(LOperand* op,
                                         FloatRegister flt_scratch,
                                         DoubleRegister dbl_scratch);
-  int32_t ToRepresentation(LConstantOperand* op, const Representation& r) const;
+  int32_t ToRepresentation_donotuse(LConstantOperand* op,
+                                    const Representation& r) const;
   int32_t ToInteger32(LConstantOperand* op) const;
   Smi* ToSmi(LConstantOperand* op) const;
   double ToDouble(LConstantOperand* op) const;