MIPS: Correctify instanceof and make it optimizable.

src/full-codegen/mips64/full-codegen-mips64.cc

Index: src/full-codegen/mips64/full-codegen-mips64.cc
diff --git a/src/full-codegen/mips64/full-codegen-mips64.cc b/src/full-codegen/mips64/full-codegen-mips64.cc
index 5483258f6d87a00a8a2e171236f10bd47abc924f..e39753d8e72bec33b7724e6b805b325d16e5e0dd 100644
--- a/src/full-codegen/mips64/full-codegen-mips64.cc
+++ b/src/full-codegen/mips64/full-codegen-mips64.cc
@@ -5120,12 +5120,14 @@ void FullCodeGenerator::VisitCompareOperation(CompareOperation* expr) {
       break;
 
     case Token::INSTANCEOF: {
-      VisitForStackValue(expr->right());
-      InstanceofStub stub(isolate(), InstanceofStub::kNoFlags);
+      VisitForAccumulatorValue(expr->right());
+      __ mov(a0, result_register());
+      __ pop(a1);
+      InstanceOfStub stub(isolate());
       __ CallStub(&stub);
-      PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
-      // The stub returns 0 for true.
-      Split(eq, v0, Operand(zero_reg), if_true, if_false, fall_through);
+      PrepareForBailoutBeforeSplit(expr, false, NULL, NULL);
+      __ LoadRoot(a4, Heap::kTrueValueRootIndex);
+      Split(eq, v0, Operand(a4), if_true, if_false, fall_through);
       break;
     }