Fixes buggy FPU tests for MIPS hardware.

runtime/vm/simulator_mips.h

Index: runtime/vm/simulator_mips.h
===================================================================
--- runtime/vm/simulator_mips.h	(revision 24149)
+++ runtime/vm/simulator_mips.h	(working copy)
@@ -50,7 +50,12 @@
   double get_fregister_double(FRegister freg) const;
   int64_t get_fregister_long(FRegister freg) const;
 
+  void set_dregister_bits(DRegister freg, int64_t value);
+  void set_dregister(DRegister freg, double value);
 
+  int64_t get_dregister_bits(DRegister freg) const;
+  double get_dregister(DRegister freg) const;
+
   // Accessor for the pc.
   void set_pc(int32_t value) { pc_ = value; }
   int32_t get_pc() const { return pc_; }
@@ -95,12 +100,14 @@
 
   // Dart generally calls into generated code with 5 parameters. This is a
   // convenience function, which sets up the simulator state and grabs the
-  // result on return.
+  // result on return. When fp_return is true the return value is the D0
+  // floating point register. Otherwise, the return value is V1:V0.
   int64_t Call(int32_t entry,
                int32_t parameter0,
                int32_t parameter1,
                int32_t parameter2,
-               int32_t parameter3);
+               int32_t parameter3,
+               bool fp_return = false);
 
   // Runtime and native call support.
   enum CallKind {