Merge 133885 - Web Inspector: Add option to disable rulers (Elements panel)

Merge 133885 - Web Inspector: Add option to disable rulers (Elements panel)
https://bugs.webkit.org/show_bug.cgi?id=101554

Reviewed by Pavel Feldman.

A new setting, showMetricsRulers, has been introduced (off by default, so users need to opt in to see the rulers).
The setting value is passed into InspectorDOMAgent, down to the InspectorOverlayPage, which affects the drawGrid() and
drawRulers() calls. As a side effect, the issue when the rulers were painted for elements having no renderers has been fixed.

No new tests, a UI change.

* English.lproj/localizedStrings.js: Add "Show rulers" string.
* inspector/InspectorDOMAgent.cpp:
(WebCore::InspectorDOMAgent::highlightConfigFromInspectorObject): Copy over the showRulers value.
* inspector/InspectorOverlay.cpp:
(WebCore::buildObjectForHighlight): Copy over the showRulers value.
* inspector/InspectorOverlay.h:
(HighlightConfig): Add |bool showRulers|.
(WebCore::Highlight::Highlight): Initialize fields.
(Highlight): Add |bool showRulers|.
(WebCore::Highlight::setDataFromConfig):
* inspector/InspectorOverlayPage.html:
* inspector/front-end/DOMAgent.js: Make use of WebInspector.settings.showMetricsRulers when building the highlight DTO.
* inspector/front-end/Settings.js: Add showMetricsRulers.
* inspector/front-end/SettingsScreen.js:
(WebInspector.GenericSettingsTab): Add "Show rulers" checkbox in the Elements panel section.

TBR=apavlov@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=134415