Revert of [wasm][asm.js] Turn on asm.js -> WebAssembly by default. (patchset...

Revert of [wasm][asm.js] Turn on asm.js -> WebAssembly by default. (patchset #2 id:20001 of https://codereview.chromium.org/2625823006/ )

Reason for revert:
Suspecting this CL is causing these tests to fail:
fast/workers/worker-shared-asm-buffer.html
virtual/sharedarraybuffer/fast/workers/worker-shared-asm-buffer.html

From the layout test results, it seems that turning on asm.js will append some console results to the test outcome.
Example build:
https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Trusty/builds/22022

Original issue's description:
> [wasm][asm.js] Turn on asm.js -> WebAssembly by default.
>
> BUG=v8:4203
> R=danno@chromium.org,titzer@chromium.org,jochen@chromium.org
>
> Review-Url: https://codereview.chromium.org/2625823006
> Cr-Commit-Position: refs/heads/master@{#443289}
> Committed: https://chromium.googlesource.com/chromium/src/+/7417bea53a78a97ae815479e5d73cf0840d90c88

TBR=jochen@chromium.org,bradnelson@google.com,danno@chromium.org,titzer@chromium.org,bradnelson@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4203

Review-Url: https://codereview.chromium.org/2631543002
Cr-Commit-Position: refs/heads/master@{#443330}

content/public/common/content_features.cc

@@ -12,7 +12,7 @@ namespace features {
 // Enables asm.js to WebAssembly V8 backend.
 // http://asmjs.org/spec/latest/
 const base::Feature kAsmJsToWebAssembly{"AsmJsToWebAssembly",
-                                        base::FEATURE_ENABLED_BY_DEFAULT};
+                                        base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enables brotli "Accept-Encoding" advertising and "Content-Encoding" support.
 // Brotli format specification: http://www.ietf.org/id/draft-alakuijala-brotli