MIPS: Fix mjsunit/regress/regress-5213

Fix failure in mjsunit/regress/regress-5213. When bailout happens,
the double registers are not properly loaded if exponent_type() is
INTEGER (this happens in optimized version of code only).

BUG=mjsunit/regress/regress-5213

Review-Url: https://codereview.chromium.org/2175633003
Cr-Commit-Position: refs/heads/master@{#38013}

src/mips/code-stubs-mips.cc

@@ -859,11 +859,11 @@ void MathPowStub::Generate(MacroAssembler* masm) {
 
   // double_exponent may not contain the exponent value if the input was a
   // smi.  We set it with exponent value before bailing out.
+  __ bind(&bail_out);
   __ mtc1(exponent, single_scratch);
   __ cvt_d_w(double_exponent, single_scratch);
 
   // Returning or bailing out.
-  __ bind(&bail_out);
   __ push(ra);
   {
     AllowExternalCallThatCantCauseGC scope(masm);

src/mips64/code-stubs-mips64.cc

@@ -856,11 +856,11 @@ void MathPowStub::Generate(MacroAssembler* masm) {
 
   // double_exponent may not contain the exponent value if the input was a
   // smi.  We set it with exponent value before bailing out.
+  __ bind(&bail_out);
   __ mtc1(exponent, single_scratch);
   __ cvt_d_w(double_exponent, single_scratch);
 
   // Returning or bailing out.
-  __ bind(&bail_out);
   __ push(ra);
   {
     AllowExternalCallThatCantCauseGC scope(masm);