Add checks to runtime functions.

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index 99728b5b8932f8be9e8aa86178eef14d55e8671c..b088d42a29e3991f109f6dfe52f16160c07f216e 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -1285,12 +1285,10 @@ void LCodeGen::DoDateField(LDateField* instr) {
   ASSERT(!scratch.is(scratch0()));
   ASSERT(!scratch.is(object));
 
-#ifdef DEBUG
-  __ AbortIfSmi(object);
+  __ And(at, object, Operand(kSmiTagMask));
+  DeoptimizeIf(eq, instr->environment(), at, Operand(zero_reg));
   __ GetObjectType(object, scratch, scratch);
-  __ Assert(eq, "Trying to get date field from non-date.",
-      scratch, Operand(JS_DATE_TYPE));
-#endif
+  DeoptimizeIf(ne, instr->environment(), scratch, Operand(JS_DATE_TYPE));
 
   if (index->value() == 0) {
     __ lw(result, FieldMemOperand(object, JSDate::kValueOffset));
@@ -1968,9 +1966,7 @@ void LCodeGen::DoGetCachedArrayIndex(LGetCachedArrayIndex* instr) {
   Register input = ToRegister(instr->InputAt(0));
   Register result = ToRegister(instr->result());
 
-  if (FLAG_debug_code) {
-    __ AbortIfNotString(input);
-  }
+  __ AbortIfNotString(input);
 
   __ lw(result, FieldMemOperand(input, String::kHashFieldOffset));
   __ IndexFromHash(result, result);