Fix BMC 21362 [L10N] CHT/JPN: Pasting JPN texts generates Tofu at the end
Fix BMC 21362 [L10N] CHT/JPN: Pasting JPN texts generates Tofu at the end

When Qt's richTextBox are pasted HTML content copied from chromium, an extra
invalid character will be added in the end during decoding HTML.

Fix this by only provide plain text copy/paste.

Reviewed by James


Former-commit-id: 6c37aab88da8cf22a36d6cc3aa9e0ec687340c22
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser