Precompute cursor pixel rects in EditorComponent and pass them down
Implement CursorComponent::shouldComponentUpdate

This prevents re-rendering cursors on blink, since only the class on
the outer component changes.
Precompute pixel rects for highlight decorations in EditorComponent
Restore pausing of cursor blink on cursor movement
:lipstick:
Add HighlightComponent::shouldComponentUpdate
Only pause cursor blink when cursors actually move

Not when they are just repositioned due to lineHeight/charWidth changes
Merge pull request #2735 from atom/ns-react-precompute-pixel-rects

Compute pixel rects of cursors and highlights in EditorComponent