[builtins] fix load of surrogate pair for BE platform

src/compiler/js-builtin-reducer.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/js-builtin-reducer.h"
 
 #include "src/compilation-dependencies.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 1123 matching lines @@
               graph()->NewNode(simplified()->NumberBitwiseAnd(), trail,
                                jsgraph()->Int32Constant(0xFC00)),
               jsgraph()->Int32Constant(0xDC00));
           Node* branch3 = graph()->NewNode(common()->Branch(BranchHint::kTrue),
                                            check3, if_true2);
           Node* if_true3 = graph()->NewNode(common()->IfTrue(), branch3);
           Node* vtrue3;
           {
             vtrue3 = graph()->NewNode(
                 simplified()->NumberBitwiseOr(),
+// Need to swap the order for big-endian platforms
+#if V8_TARGET_BIG_ENDIAN
+                graph()->NewNode(simplified()->NumberShiftLeft(), lead,
+                                 jsgraph()->Int32Constant(16)),
+                trail);
+#else
                 graph()->NewNode(simplified()->NumberShiftLeft(), trail,
                                  jsgraph()->Int32Constant(16)),
                 lead);
+#endif
           }
 
           Node* if_false3 = graph()->NewNode(common()->IfFalse(), branch3);
           Node* vfalse3 = lead;
           if_true2 = graph()->NewNode(common()->Merge(2), if_true3, if_false3);
           vtrue2 =
               graph()->NewNode(common()->Phi(MachineRepresentation::kWord32, 2),
                                vtrue3, vfalse3, if_true2);
         }
 
@@ skipping 282 matching lines @@
   return jsgraph()->simplified();
 }
 
 JSOperatorBuilder* JSBuiltinReducer::javascript() const {
   return jsgraph()->javascript();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8