X64: Convert HeapNumbers that contain valid smi values to smis in binop-stub.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index bf4e22e026a850076d54b601dac981dded40b63a..b0971663a03fc44bae2863826cb49db67c8d9cf7 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -1320,6 +1320,7 @@ void MacroAssembler::SmiAndConstant(Register dst, Register src, Smi* constant) {
 
 void MacroAssembler::SmiOr(Register dst, Register src1, Register src2) {
   if (!dst.is(src1)) {
+    ASSERT(!src1.is(src2));
     movq(dst, src1);
   }
   or_(dst, src2);
@@ -1340,6 +1341,7 @@ void MacroAssembler::SmiOrConstant(Register dst, Register src, Smi* constant) {
 
 void MacroAssembler::SmiXor(Register dst, Register src1, Register src2) {
   if (!dst.is(src1)) {
+    ASSERT(!src1.is(src2));
     movq(dst, src1);
   }
   xor_(dst, src2);