Continues Latin-1 support. All tests pass with ENABLE_LATIN_1 flag.

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 7dd828136b22afaa5f255977d07618d77f9dc3d5..bf61f75c4bb8cba259054674ba7c33e8f6575f4c 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -5473,16 +5473,32 @@ void StringCompareStub::GenerateCompareFlatAsciiStrings(MacroAssembler* masm,
   // Compare lengths (precomputed).
   __ bind(&compare_lengths);
   __ SmiTest(length_difference);
+#ifndef ENABLE_LATIN_1
   __ j(not_zero, &result_not_equal, Label::kNear);
+#else
+  Label length_not_equal;
+  __ j(not_zero, &length_not_equal, Label::kNear);
+#endif
 
   // Result is EQUAL.
   __ Move(rax, Smi::FromInt(EQUAL));
   __ ret(0);
 
   Label result_greater;
+#ifdef ENABLE_LATIN_1
+  Label result_less;
+  __ bind(&length_not_equal);
+  __ j(greater, &result_greater, Label::kNear);
+  __ jmp(&result_less, Label::kNear);
+#endif
   __ bind(&result_not_equal);
   // Unequal comparison of left to right, either character or length.
+#ifndef ENABLE_LATIN_1
   __ j(greater, &result_greater, Label::kNear);
+#else
+  __ j(above, &result_greater, Label::kNear);
+  __ bind(&result_less);
+#endif
 
   // Result is LESS.
   __ Move(rax, Smi::FromInt(LESS));