The max line box API, introduced in bug 780259, is not correctly handling RTL text. Text indentation when direction is RTL is broken due to the algorithm we chose to use for max line box width calculation (from the far left edge), and because text indents are not symmetric when considering RTL vs. LTR text. Further, dbaron comments in bug 803211 that RTL is broken in the following ways with this approach: > * it's not clear to me that positioning things at the left edge is the right > thing for RTL > * RTL + text-indent is also different from what I originally thought; given > that this code adjusts mRightEdge just like text-indent, we end up erasing the > text indent (rather than indenting out the other end, as I was originally > worried)