IndexedDB: Replace IDL operation overloading with ScriptValue handling

The IDB spec has many IDL methods that take |any key| and in prose
have "if key is not a valid key or IDBKeyRange, throw; otherwise ...";
these ended up being implemented incrementally in Blink using
overloads in the IDL and .h/.cpp, and counting on nonstandard overload
handling in the code generator.

Update the Blink IDLs to mostly match the spec IDLs, and do the
ScriptValue to IDBKey or IDBKeyRange conversion via explicit calls to
a binding helper. This simplifies the IDL and implementations, and
will make future additions easier.

No behavior changes.

R=haraken@chromium.org

Review URL: https://chromiumcodereview.appspot.com/22893058

git-svn-id: svn://svn.chromium.org/blink/trunk@156716 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Introduce RenderLayer::scrollsWithRespectTo including layout tests.

scrollsWithRespectTo determines whether 2 RenderLayers can
scroll relative to each other. It does this by trying to
find the common containing block between the two
RenderLayers - if it can find a common containing block
before running into a scrollable ancestor for either layer,
then the two RenderLayers are static with respect to each
other. If there is no common containing block, or if there
is a scrollable layer in the way, then the scroll relative
to each other.

BUG=

Review URL: https://chromiumcodereview.appspot.com/23091002

git-svn-id: svn://svn.chromium.org/blink/trunk@156717 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove WebMediaSourceNew references in Blink code.

BUG=272993
TEST=All existing LayoutTests still pass.

Review URL: https://chromiumcodereview.appspot.com/23136009

git-svn-id: svn://svn.chromium.org/blink/trunk@156718 bbb929c8-8fbe-4397-9dbb-9b2b20218538