MIPS: Fix zlib critical performance regression.

The very low score on zlib benchmark is caused by
huge number of deoptimizations inside BinaryOpIC stubs
when arguments are boolean.

TEST=
BUG=
R=plind44@gmail.com

Review URL: https://codereview.chromium.org/136193011

Patch from Dusan Milosavljevic <Dusan.Milosavljevic@rt-rk.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19006 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/lithium-codegen-mips.cc

@@ -4800,8 +4800,9 @@ void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr) {
     // Performs a truncating conversion of a floating point number as used by
     // the JS bitwise operations.
     Label no_heap_number, check_bools, check_false;
-    __ Branch(&no_heap_number, ne, scratch1, Operand(at));  // HeapNumber map?
-    __ mov(scratch2, input_reg);
+    // Check HeapNumber map.
+    __ Branch(USE_DELAY_SLOT, &no_heap_number, ne, scratch1, Operand(at));
+    __ mov(scratch2, input_reg);  // In delay slot.
     __ TruncateHeapNumberToI(input_reg, scratch2);
     __ Branch(&done);