Web Inspector: fix DefaultTextEditor's broken backspace

Web Inspector: fix DefaultTextEditor's broken backspace
https://bugs.webkit.org/show_bug.cgi?id=107130

Patch by Andrey Lushnikov <lushnikov@chromium.org> on 2013-01-17
Reviewed by Pavel Feldman.

Source/WebCore:

Remove css "position: relative;" style from "webkit-line-content" class, which
somehow brakes editing experience. Remove "height: 100%" from text-editor-overlay-highlight
class and cast necessary height via inserting "&nbsp;" into overlay span elements.

No new tests: no change in behaviour.

* inspector/front-end/DefaultTextEditor.js:
(WebInspector.TextEditorMainPanel.prototype._appendOverlayHighlight):
* inspector/front-end/textEditor.css:
(.text-editor-overlay-highlight):

LayoutTests:

Fix test expected results to correspond to changes.

* inspector/editor/text-editor-highlight-regexp-expected.txt:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@139980 268f45cc-cd09-0410-ab3c-d52691b4dbfc