Fix CustomContent display issue.

During certain transition animations, the X offset value is computed,
taking into account the translation value set by the transition effect.
Preserved the right behavior by using child.getLeft() to compute the value,
without including the X translation.

Change-Id: I25acf6e4bae1db9a2c12525125a4994e16c40dfe
Merge remote-tracking branch 'cm/cm-11.0' into cm-11.0