fix paste of clipboard content

[jcppman]

closes #2270

use copiedStyle only if the pasted content source is copiedText.

[asturur]

Please, i cannot reproduce it on kitchensink.
Could you please tell me where did you found the bug
version of fabricjs ( number or if you pulled github ) and browser used. ( and version )

[jcppman]

Hi, I'm using the master branch, latest commit: 2d38f9e

Environment

• Chrome 43
• Firefox 38
• Safari 8

OS: Mac OSX

Steps:

1. copy url from browser's address bar
2. open kitchensink
3. double-click an IText and paste

To reproduce the bug, make sure you don't copy anything from IText before, otherwise even if you copy anything from other places which doesn't set this.copiedStyles, previous value is still there.

So it means that in current master branch, in order to make paste of an IText work, user has to copy a value from itself frist.

[asturur]

ok i ll check it as priority and see where the problem came from.

[jcppman]

Thank you for the quick response :)

The problem comes from _insertStyles cuz in insertChars we pass a true to use copiedStyle but in this scenario it is undefined.

This PR is confirmed to fix this problem on all browsers I tried but I don't have any tablet so this part need to be comfirmed

[asturur]

@kangax this is fine, you should merge this.

[asturur]

need to resubmit with additional fix