MIPS: Add rounding support in simulator and RINT instruction.

test/cctest/test-disasm-mips.cc

Index: test/cctest/test-disasm-mips.cc
diff --git a/test/cctest/test-disasm-mips.cc b/test/cctest/test-disasm-mips.cc
index 5789a23390f392edb6db3a0173ebc75698aff1b4..09f004e3c5158a067d2a6770840363c8807642c7 100644
--- a/test/cctest/test-disasm-mips.cc
+++ b/test/cctest/test-disasm-mips.cc
@@ -538,6 +538,8 @@ TEST(Type1) {
 
     COMPARE(min(D, f3, f4, f5), "462520dc       min.d    f3, f4, f5");
     COMPARE(max(D, f3, f4, f5), "462520de       max.d    f3, f4, f5");
+    COMPARE(rint(D, f8, f6), "4620321a       rint.d    f8, f6");
+
     VERIFY_RUN();
   }
 }