Revert of [simd.js] Disable SIMD polyfill. (patchset #2 id:20001 of...

Revert of [simd.js] Disable SIMD polyfill. (patchset #2 id:20001 of https://codereview.chromium.org/1305923005/ )

Reason for revert:
Breaks simdjs performance tests. See:
https://paste.googleplex.com/5883927122149376

Original issue's description:
> [simd.js] Disable SIMD polyfill.
>
> Disable the polyfill in simd.js tests as the functions for Phase 1 have been implemented.
>
> BUG=v8:4124
> LOG=N
>
> R=bbudge@chromium.org, bmeurer@chromium.org, littledan@chromium.org
>
> Committed: https://crrev.com/749ba3a13558cb018a2ec783e5dfb56d2f8528d8
> Cr-Commit-Position: refs/heads/master@{#30452}

TBR=littledan@chromium.org,bmeurer@chromium.org,bradnelson@chromium.org,bbudge@chromium.org,gdeepti@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4124

Review URL: https://codereview.chromium.org/1308003003

Cr-Commit-Position: refs/heads/master@{#30470}

test/simdjs/SimdJs.json

@@ -9,6 +9,7 @@
   ],
   "resources": [
     "test/simdjs/data/src/benchmarks/base.js",
+    "test/simdjs/data/src/ecmascript_simd.js",
     "test/simdjs/harness-adapt.js",
     "test/simdjs/harness-finish.js",
     "test/simdjs/data/src/benchmarks/kernel-template.js",

test/simdjs/generate.py

@@ -37,6 +37,7 @@ output = {
   'units': 'ms',
   'resources': [
     'test/simdjs/data/src/benchmarks/base.js',
+    'test/simdjs/data/src/ecmascript_simd.js',
     'test/simdjs/harness-adapt.js',
     'test/simdjs/harness-finish.js'
   ] + ['test/simdjs/data/src/benchmarks/%s.js' % t for t in tests],

test/simdjs/harness-adapt.js

@@ -21,9 +21,8 @@ load = function(filename) {
   }
 };
 
-// To enable SIMD polyfill, load ecmascript_simd.js here and
-// add to resources in SimdJs.json as well as the script to
-// re-generate SimdJs.json.
+// TODO(bbudge): Drop when polyfill is not needed.
+load('ecmascript_simd.js');
 
 load('base.js');