Rename ScriptElement to ScriptLoader

This change renames ScriptElement to ScriptLoader.
This also does related renames:
- ScriptElementClient -> ScriptLoaderClient
- HTMLScriptElement::m_scriptElement -> HTMLScriptElement::m_loader
- Ditto for SVGScriptElement

As a bonus, ScriptLoaderClient got its own header file
which hides ScriptLoader from majority of core files.

BUG=240592
TEST=none
R=hayato@chromium.org

Review URL: https://codereview.chromium.org/18261015

git-svn-id: svn://svn.chromium.org/blink/trunk@153755 bbb929c8-8fbe-4397-9dbb-9b2b20218538
createStringWithMirroredCharacters shouldn't use bloatedCharacters

We just need a Latin-1 path for this function.

R=eseidel
BUG=254708

Review URL: https://chromiumcodereview.appspot.com/18870008

git-svn-id: svn://svn.chromium.org/blink/trunk@153756 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove accesskey caching in Document.

This change simplifies Document by removing its ability to cache the mapping
between accesskeys and elements. Now getElementByAccessKey() member function
traverses all elements under the document every time it is called.

See bug 226839 for further details about motivation of this change.

Document's member function getElementByAccessKey() is moved to TreeScope,
because it needs to recurse on the shadow roots.

The behavior of accesskey should not change.

BUG=226839
R=jamesr@chromium.org,morrita@chromium.org

Review URL: https://chromiumcodereview.appspot.com/18684003

git-svn-id: svn://svn.chromium.org/blink/trunk@153757 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Implemented StyleSheetCollection.

This is a part of refactoring DocumentStyleSheetCollection.
I added actual stylesheet collection, i.e. StyleSheetCollection and made DocumentStyleSheetCollection be a manager of instances of the added class.
Currently, there is only 1 StyleSheetCollection for document tree.
I will add StyleSheetCollections for shadow trees.

BUG=244314

Review URL: https://chromiumcodereview.appspot.com/18036004

git-svn-id: svn://svn.chromium.org/blink/trunk@153758 bbb929c8-8fbe-4397-9dbb-9b2b20218538
REGRESSION(r153385): Linux: Unreadable disabled selected options in listbox <select>.

r153385 added a ruleset to themeWin.css. It affects Linux too
unexpectedly. We override style in themeChromiumLinux.css so that it
has same style before r153385.

BUG=

Review URL: https://chromiumcodereview.appspot.com/18293005

git-svn-id: svn://svn.chromium.org/blink/trunk@153759 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Custom Elements should invoke the attributeChangedCallback for changes.

Currently attributeChangedCallback is invoked any time an attribute is
set, but per the spec, this should be when the attribute is *changed*.
<https://dvcs.w3.org/hg/webcomponents/raw-file/b3bb5cb82773/spec/custom/index.html#custom-element-lifecycle>

R=esprehn@chromium.org
BUG=245518

Review URL: https://chromiumcodereview.appspot.com/18500018

git-svn-id: svn://svn.chromium.org/blink/trunk@153760 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use toSVGFontElement() instead of static_cast<SVGFontElement*>

As a step to change static_cast with toXXX, static_cast<SVGFontElement*> can
be changed with toSVGFontElement().

BUG=

Review URL: https://chromiumcodereview.appspot.com/18045006

git-svn-id: svn://svn.chromium.org/blink/trunk@153761 bbb929c8-8fbe-4397-9dbb-9b2b20218538