Distinguish required IDL extended attribute values, remove most optional

This CL distinguishes extended attributes with a required value with any
value allowed ("*") from optional values ("|*"), and removes
most optional values.

This leaves only 1 optional value, Reflect.
Reflect is used in ~300 places, ~20 with a value, ~280 without.
From discussion and spec, it’s clearly useful for the value to be optional.
(The IDL attribute should reflect a content attribute; these usually have
 the same name, but sometimes not, hence the optional value.)
https://sites.google.com/a/chromium.org/dev/blink/webidl/blink-idl-extended-attributes#TOC-Reflect-a-

Also some refactoring to Python IDL validator.

Followup to:
Give explicit argument to EnabledAtRuntime (IDL extended attribute)
https://codereview.chromium.org/23667002/

Review URL: https://chromiumcodereview.appspot.com/23564003

git-svn-id: svn://svn.chromium.org/blink/trunk@156842 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add HTMLInputType::m_inputTypeView.

InputTypeView functions are called through m_inputTypeView though
m_inputTypeView is identical to m_inputType for now.

This is a preparation to support author shadow DOM for INPUT elements.

BUG=274205
TEST=none; no behavior changes.

Review URL: https://chromiumcodereview.appspot.com/23458005

git-svn-id: svn://svn.chromium.org/blink/trunk@156844 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: add Reveal in Elements panel option to layer context menu

- handle DOMNode targets in appendApplicableItems() of Element panel and its descriptor;
- handle contextmenu event in LayerTree and Layers3DView;
- dispatch appendApplicableItems with a DOMNode of layer owner from the tree and the 3d view;

BUG=
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/23137017

git-svn-id: svn://svn.chromium.org/blink/trunk@156845 bbb929c8-8fbe-4397-9dbb-9b2b20218538