[DevTools] Switch from DIP to CSS pixels in device mode.

Rulers, grid and media queries are now rendered in CSS pixels.
Additionally, a content size rectangle is drawn for visual feedback.

BUG=none

Review URL: https://codereview.chromium.org/351303003

git-svn-id: svn://svn.chromium.org/blink/trunk@177098 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: [CodeMirror] add support for camel case movements.

Camel-case movement allows movement between
subwords of camel-case-written words or phrases.

This patch adds support for camel-case movement to the DevTools editor.
The camel-case movement is done via Alt-Left/Alt-Right on Win and Linux,
and via Ctrl-Left/Ctrl-Right on Mac.

Review URL: https://codereview.chromium.org/357483007

git-svn-id: svn://svn.chromium.org/blink/trunk@177099 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Check if the context is properly initialized before retrieving its script state.

BUG=389118

Review URL: https://codereview.chromium.org/357873003

git-svn-id: svn://svn.chromium.org/blink/trunk@177100 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Resolve percent lengths for abs. positioned tables against padding box.

According to CSS2.1: "[...] absolutely positioned elements whose
containing block is based on a block container element, the percentage
is calculated with respect to the width of the padding box of that
element".

BUG=366123

Review URL: https://codereview.chromium.org/341523002

git-svn-id: svn://svn.chromium.org/blink/trunk@177101 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: disable DOMAgent when profiler is active

BUG=381115

Review URL: https://codereview.chromium.org/354023002

git-svn-id: svn://svn.chromium.org/blink/trunk@177102 bbb929c8-8fbe-4397-9dbb-9b2b20218538