[Table] Truncated icons persist in cells even when text isn't truncated

[tgreenwatts]

To reproduce:
On the Formatted Content example, expand the date column to where it does not need the truncation ellipsis
Expected: Truncation ellipsis goes away
Actual: Ellipsis stays
Now scroll down and come back
Expected: Scrolling changes nothing
Actual: Now the ellipsis is gone!

This is a Regression

[adidahiya]

almost certainly due to #998

[cmslewis]

Yep, probably an erroneous @PureRender or shouldComponentUpdate somewhere.