Double field values need sNaN -> qNaN canonicalization.

test/mjsunit/regress/regress-undefined-nan.js

 // Copyright 2015 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.
 
 // Flags: --allow-natives-syntax
 
 function loader(dst, src, i) {
   dst[i] = src[i];
 }
 
 var ab = new ArrayBuffer(8);
 var i_view = new Int32Array(ab);
 i_view[0] = 0xFFF7FFFF;
 i_view[1] = 0xFFF7FFFF;
 var f_view = new Float64Array(ab);
 
 var fixed_double_elements = new Float64Array(1);
-fixed_double_elements[0] = f_view[0];
+
+function opt_store() { fixed_double_elements[0] = f_view[0]; }
+
+opt_store();
+opt_store();
+%OptimizeFunctionOnNextCall(opt_store);
+opt_store();
+
+var i32 = new Int32Array(fixed_double_elements.buffer);
+assertEquals(i_view[0], i32[0]);
+assertEquals(i_view[1], i32[1]);
 
 var doubles = [0.5];
 loader(doubles, fixed_double_elements, 0);
 loader(doubles, fixed_double_elements, 0);
 %OptimizeFunctionOnNextCall(loader);
 loader(doubles, fixed_double_elements, 0);
 assertTrue(doubles[0] !== undefined);