Web Inspector: Don't include error message text in the editor buffer.

https://bugs.webkit.org/show_bug.cgi?id=103932

Reviewed by Alexander Pavlov.

Source/WebCore:

Skip entire decoration content when collecting dirty regions.

* inspector/front-end/DefaultTextEditor.js:
(WebInspector.TextEditorMainPanel.prototype._collectLinesFromDOM):

LayoutTests:

* inspector/editor/editor-test.js:
(initialize_EditorTests.InspectorTest.getLineElement):
(initialize_EditorTests):
* inspector/editor/text-editor-type-over-decoration-expected.txt: Added.
* inspector/editor/text-editor-type-over-decoration.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@136703 268f45cc-cd09-0410-ab3c-d52691b4dbfc