Initialize maths result array in JS.

src/runtime/runtime-maths.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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/assembler.h"
 #include "src/base/utils/random-number-generator.h"
 #include "src/codegen.h"
@@ skipping 50 matching lines @@
 }
 
 
 RUNTIME_FUNCTION(Runtime_RemPiO2) {
   SealHandleScope shs(isolate);
   DisallowHeapAllocation no_gc;
   DCHECK(args.length() == 2);
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
   CONVERT_ARG_CHECKED(JSTypedArray, result, 1);
   RUNTIME_ASSERT(result->byte_length() == Smi::FromInt(2 * sizeof(double)));
-  void* backing_store = JSArrayBuffer::cast(result->buffer())->backing_store();
-  double* y = static_cast<double*>(backing_store);
+  FixedFloat64Array* array = FixedFloat64Array::cast(result->elements());
+  double* y = static_cast<double*>(array->DataPtr());
   return Smi::FromInt(fdlibm::rempio2(x, y));
 }
 
 
 static const double kPiDividedBy4 = 0.78539816339744830962;
 
 
 RUNTIME_FUNCTION(Runtime_MathAtan2) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
@@ skipping 172 matching lines @@
   uint16_t seeds[kSize];
   do {
     isolate->random_number_generator()->NextBytes(seeds,
                                                   kSize * sizeof(*seeds));
   } while (!(seeds[0] && seeds[1] && seeds[2] && seeds[3]));
   for (int i = 0; i < kSize; i++) array->set(i, Smi::FromInt(seeds[i]));
   return *isolate->factory()->NewJSArrayWithElements(array);
 }
 }  // namespace internal
 }  // namespace v8