This must be a regression of bug 1213589. When removing whole text from an editor, the editor removes moz-<br> after removing all nodes. Immediately before the remove, moz-<br> becomes <br>. So, IMEContentObserver::AttributeChanged() detects the native text length for the <br> element changing from 0 to 2 (on Windows) or 1 (on the other platforms). However, the call of ContentEventHandler::GetFlatTextLengthInRange() in IMEContentObserver::AttributeChanged() returns 2 (on Windows) or 1 (on the other platforms). Although, it tries to get the length from the start of the editor to before aElement, it always includes the length of the line breaker caused by the end node.
The reason is, ContentEventHandler::GetFlatTextLengthInRange() always adds the line breaker's length for the end node without checking the range includes open tag of the end node. Therefore, this patch adds the check into ContentEventHandler::GetFlatTextLengthInRange(). So, ContentEventHandler::GetFlatTextLengthInRange() becomes to support NodePositionBefore() for the end of the range.
Additionally, this patch fixes a bug at appending text node length. In the loop, |aEndPosition| shouldn't be referred because it may be hacked with |endPosition|. So, detecting the last text node should be compared with |endPosition|.
For making the method code safer, this changes whole |aEndPosition| after defining |endPosition| is replaced with |endPosition|.
MozReview-Commit-ID: FUp2nxuQHnO
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extra : rebase_source : 611992faf95082ce8ae005b7bcce90a3bea4f99e
7a28856eef