[builtins] fix load of surrogate pair for BE platform

src/builtins/builtins-string.cc

Index: src/builtins/builtins-string.cc
diff --git a/src/builtins/builtins-string.cc b/src/builtins/builtins-string.cc
index 6b14e2510b773ea5f5004334041e174b043e3846..efd9d23c9bc1892162903d3187490d9d2ad004a4 100644
--- a/src/builtins/builtins-string.cc
+++ b/src/builtins/builtins-string.cc
@@ -1380,7 +1380,12 @@ compiler::Node* LoadSurrogatePairInternal(CodeStubAssembler* assembler,
     switch (encoding) {
       case UnicodeEncoding::UTF16:
         var_result.Bind(assembler->WordOr(
+// Need to swap the order for big-endian platforms
+#if !V8_TARGET_LITTLE_ENDIAN

[caitp, 2016/10/22 06:00:25]

one more nit, I would personally prefer not negating the condition (IE do `#if
V8_TARGET_BIG_ENDIAN`, or `#if V8_TARGET_LITTLE_ENDIAN` instead. Easier to read
:)

+            assembler->WordShl(lead, assembler->Int32Constant(16)), trail));
+#else
             assembler->WordShl(trail, assembler->Int32Constant(16)), lead));
+#endif
         break;
 
       case UnicodeEncoding::UTF32: {