[webkit] inline style doesn't work for collpased range

[Garry Yao]

Reproducing Procedures

1. Open the replace by class example page in Safari4;
2. Click inside the text line to result in a collapsed the selection;
3. Click on any inline style button, e.g. Bold.
   • Actual Result: Style tag is not happened at the selection position.

[Garry Yao]

Actually the style element has been introduced, but the culprit is webkit doesn't allow selection inside the empty element, so after you begin to type, texts fall into the outside of the style.
The idea of this patch is providing a workaround to padding a bogus node (ZWNBSP) to make the selection anchored inside the element and remove the bogus node on next user action.

[Garry Yao]

The patch doesn't work with this case:

Reproducing Procedures

1. Open the replace by class example page in Safari4;
2. Click inside the text line to result in a collapsed the selection;
3. Press 'Ctrl-B', then Press 'Ctrl-I';
   • Actual Result: Both styles don't open.

[Garry Yao]

The key detection logic in previous patch is possibly be confused by shortcut keys like Ctrl-I, so I found a smarter way to check it:
We just need to check if the subsequent keystroke has actually result in any new character within the style.
I'm attaching a new patch following this approach.

[Frederico Caldeira Knabben]

I understand this is an important issue, but any fix we may propose for it is prone to be broken on special cases. We have several key combinations to caret movements, as well as the possibility of having more than one style being applied at the same time (CTRL+B + CTRL+I) or even clipboard operations being activated on different ways. I mean, it's quite easy to have any fix at our side being broken.

We have been in touch with Apple for this issue. They have demonstrated interest on fixing webkit (this is an engine bug actually), but they have brought not much more than this. Hopefully we'll have something real coming from them soon.

In any case, this is a DUP of #1272.