I think after bug 403328 lands, the mLeftIsExact / mRightIsExact outputs from nsHTMLReflowState::CalculateHypotheticalBox will become unneeded, although we may still want to assert about them in DEBUG builds. If I'm wrong, however, I think there's a pretty major bug in the code that uses them, which is that the following change needs to be made: // Well, we don't know 'left' so we have to use 'right' and // then solve for 'left' - mComputedOffsets.right = hypotheticalBox.mRight; + mComputedOffsets.right = containingBlockWidth - hypotheticalBox.mRight; rightIsAuto = PR_FALSE; since otherwise mComputedOffsets.right is in the wrong coordinate system!

So yeah. With the landing for bug 403328, it looks like mLeftIsExact is always true when the block containing the placeholder is LTR and mRightIsExact is true when it's RTL. So we can just remove those two else clauses: they're dead code.

http://hg.mozilla.org/mozilla-central/index.cgi/rev/563e158fcce0 -> fixed (for 1.9.1)