MIPS: Add support for arch. revision 6 to mips32 port.

src/base/cpu.h

Index: src/base/cpu.h
diff --git a/src/base/cpu.h b/src/base/cpu.h
index eb51674df53c445a336a2f84e17f9bf0732c4de9..d61844c151891ca8f6275c0fd882f2b2af373b6f 100644
--- a/src/base/cpu.h
+++ b/src/base/cpu.h
@@ -77,6 +77,9 @@ class CPU V8_FINAL {
   bool has_vfp3() const { return has_vfp3_; }
   bool has_vfp3_d32() const { return has_vfp3_d32_; }
 
+  // mips features
+  bool is_fp64_mode() const { return is_fp64_mode_; }
+
  private:
   char vendor_[13];
   int stepping_;
@@ -104,6 +107,7 @@ class CPU V8_FINAL {
   bool has_vfp_;
   bool has_vfp3_;
   bool has_vfp3_d32_;
+  bool is_fp64_mode_;
 };
 
 } }  // namespace v8::base