[builtins] Support SameValue and SameValueZero via runtime functions.

test/mjsunit/harmony/simd.js

Index: test/mjsunit/harmony/simd.js
diff --git a/test/mjsunit/harmony/simd.js b/test/mjsunit/harmony/simd.js
index 6330ac8338a403a014b5a5076dd0eff232f296d8..91e437c2b4e6226035341fda8767c02a4cc5734c 100644
--- a/test/mjsunit/harmony/simd.js
+++ b/test/mjsunit/harmony/simd.js
@@ -407,7 +407,7 @@ function TestSameValue(type, lanes) {
   var simdFn = SIMD[type];
   var instance = createInstance(type);
   var sameValue = Object.is
-  var sameValueZero = natives.ImportNow("SameValueZero");
+  var sameValueZero = function(x, y) { return %SameValue(x, y); }
 
   // SIMD values should not be the same as instances of different types.
   checkTypeMatrix(type, function(other) {