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

test/simdjs/harness-adapt.js

Index: test/simdjs/harness-adapt.js
diff --git a/test/simdjs/harness-adapt.js b/test/simdjs/harness-adapt.js
index 21f56002ce09cf2ed07c9b2698389a64c506d6c0..8941e2fdc1cdc66f564ff1b418f2527b5a955a7f 100644
--- a/test/simdjs/harness-adapt.js
+++ b/test/simdjs/harness-adapt.js
@@ -32,3 +32,7 @@ load('base.js');
 var console = {
   log: function(x) { print(x); },
 };
+
+// Disable value type tests for now, since the polyfill can't pass them.
+// TODO(bbudge): Drop when polyfill is not needed.
+var skipValueTests = true;