MIPS32: Fuse long and FP compare & condition in Optimizing.

This also does a minor clean-up in the assembler and
its test.

Bug: 25559148
Change-Id: I9bad3c500b592a09013b56745f70752eb284a842
diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc
index e1b13c5..67097de 100644
--- a/compiler/optimizing/instruction_simplifier.cc
+++ b/compiler/optimizing/instruction_simplifier.cc
@@ -778,9 +778,9 @@
   // Try to fold an HCompare into this HCondition.
 
   // This simplification is currently supported on x86, x86_64, ARM and ARM64.
-  // TODO: Implement it for MIPS and MIPS64.
+  // TODO: Implement it for MIPS64.
   InstructionSet instruction_set = GetGraph()->GetInstructionSet();
-  if (instruction_set == kMips || instruction_set == kMips64) {
+  if (instruction_set == kMips64) {
     return;
   }