[x64] Emit vcvttsd2si[q] when AVX is enabled.

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index e5511f5629956207234d4917fb42639e45a9ff5c..dfa777a1356e12f2dd27ca3cb79f30c07c227eb2 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -200,7 +200,7 @@ void DoubleToIStub::Generate(MacroAssembler* masm) {
     __ jmp(&check_negative);
 
     __ bind(&process_64_bits);
-    __ cvttsd2siq(result_reg, xmm0);
+    __ Cvttsd2siq(result_reg, xmm0);
     __ jmp(&done, Label::kNear);
 
     // If the double was negative, negate the integer result.
@@ -324,7 +324,7 @@ void MathPowStub::Generate(MacroAssembler* masm) {
     __ jmp(&int_exponent);
 
     __ bind(&try_arithmetic_simplification);
-    __ cvttsd2si(exponent, double_exponent);
+    __ Cvttsd2si(exponent, double_exponent);
     // Skip to runtime if possibly NaN (indicated by the indefinite integer).
     __ cmpl(exponent, Immediate(0x1));
     __ j(overflow, &call_runtime);