Merge 105140 (re-land) - Web Inspector: [TextPrompt] Autocomplete adds unwanted text that's hard ...

Merge 105140 (re-land) - Web Inspector: [TextPrompt] Autocomplete adds unwanted text that's hard to remove
https://bugs.webkit.org/show_bug.cgi?id=76058

Reviewed by Pavel Feldman.

As per the results of a war room:
- Auto-suggest only after user typing (avoid showing suggestions when navigating through the user input.)
- Do not select the first item if the suggest box is shown at the end of prompt (to allow Enter to commit the input.)
- Only show grayed autocompletion at the end of prompt (otherwise show a suggest box with the first item selected.)
- Grayed autocompletion can only be accepted with the End or Right keys.
- Enter can accept a selected suggestion item from the list, without committing the input.
- Retain the CSS model editing behavior as close to the existing one as possible.
- Enable PageUp/PageDown to navigate the suggest box items.

* inspector/front-end/StylesSidebarPane.js:
(WebInspector.StylePropertyTreeElement.prototype):
():
* inspector/front-end/TextPrompt.js:
(WebInspector.TextPrompt.prototype.set text):
(WebInspector.TextPrompt.prototype._removeSuggestionAids):
(WebInspector.TextPrompt.prototype._selectStart.moveBackIfOutside):
(WebInspector.TextPrompt.prototype._selectStart):
(WebInspector.TextPrompt.prototype.onKeyDown):
(WebInspector.TextPrompt.prototype.acceptAutoComplete):
(WebInspector.TextPrompt.prototype.complete):
(WebInspector.TextPrompt.prototype._completionsReady):
(WebInspector.TextPrompt.prototype.isCaretAtEndOfPrompt):
(WebInspector.TextPrompt.prototype.tabKeyPressed):
(WebInspector.TextPrompt.prototype.downKeyPressed):
(WebInspector.TextPrompt.prototype.pageUpKeyPressed):
(WebInspector.TextPrompt.prototype.pageDownKeyPressed):
(WebInspector.TextPrompt.SuggestBox.prototype._onNextItem):
(WebInspector.TextPrompt.SuggestBox.prototype._onPreviousItem):
(WebInspector.TextPrompt.SuggestBox.prototype.updateSuggestions):
(WebInspector.TextPrompt.SuggestBox.prototype._updateItems):
(WebInspector.TextPrompt.SuggestBox.prototype._canShowBox):
(WebInspector.TextPrompt.SuggestBox.prototype._rememberRowCountPerViewport):
(WebInspector.TextPrompt.SuggestBox.prototype._completionsReady):
(WebInspector.TextPrompt.SuggestBox.prototype.pageUpKeyPressed):
(WebInspector.TextPrompt.SuggestBox.prototype.pageDownKeyPressed):
(WebInspector.TextPrompt.SuggestBox.prototype.enterKeyPressed):

TBR=apavlov@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=105501