SIMD.js: Update Float32x4 and tests to current spec.

test/simdjs/simdjs.status

 # 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.
 
 # --------------------------------------------------------------------
 # If you add a test case to this file, please try to provide
 # an explanation of why the test fails; this may ease future
 # debugging.
 # --------------------------------------------------------------------
 
 [
 [ALWAYS, {
-  # TODO(bradnelson): Drop when test is fixed upstream.
+  # TODO(bbudge): Drop when test is fixed upstream.
   'benchmarks/aobench': SKIP,
+  'benchmarks/averageFloat64x2': SKIP,
+  'benchmarks/averageFloat64x2Load': SKIP,
+  'benchmarks/mandelbrot': SKIP,
+  'benchmarks/sinx4': SKIP,
 
   # TODO(bbudge): Drop this when simd implementation is faster.
   'benchmarks/memcpy': SKIP,
 }],
 
 ######################################################################
 ['byteorder == big', {
   # shell_test_runner requires little-endian, skip it on big-endian.
   'shell_test_runner': [SKIP],
 }],  # 'byteorder == big'
 
 ]