Make calls to AtomicString(const String&) explicit in html/

Make calls to AtomicString(const String&) explicit in html/ and avoid
useless conversions from String to AtomicString when possible.

This is one step towards making the AtomicString(const String&) constructor
explicit. This CL takes care only of the html/ part so that it is more
easily reviewable.

R=eseidel
BUG=323739

Review URL: https://codereview.chromium.org/108313015

git-svn-id: svn://svn.chromium.org/blink/trunk@164418 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move SubstituteData processing to ResourceFetcher

Use a technique similar to how data: images are processed. Namely, pre-populate a Resource and put it in the MemoryCache which can than be treated as a cache hit.

In the case of main resources, which we don't normally reuse, we allow the Resource created from the SubstituteData to live in the MemoryCache temporarily. When the "cache hit" occurs, we remove it to ensure it isn't actually reused.

BUG=

Review URL: https://codereview.chromium.org/118433003

git-svn-id: svn://svn.chromium.org/blink/trunk@164423 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add SourceAlpha support to accelerated CSS filter effects (aka Skia SkImageFilter DAG) path.

BUG=331362

Review URL: https://codereview.chromium.org/123293002

git-svn-id: svn://svn.chromium.org/blink/trunk@164424 bbb929c8-8fbe-4397-9dbb-9b2b20218538