UI Text gets out of Rect Transform bounds when changing left margin under Extra settings.

Steps to repro:
1. Create a new project.
2. Import 'Essential Resources' and 'Examples and Extras' form Windows > TextmeshPro.
3. Open the file 01- Single Line TextMesh Pro found under Assets -> TextMeshPro -> Examples & Extras -> Scenes
4. Hit Simple Example object in the hierarchy view
5. Open the Extra Settings rollout
6. Change Left margin to 100
7. Delete 0 at unit's place to make it 10.

Actual Result:
UI Text gets out of Rect Transform bounds when changing left margin under Extra settings.

Expected Result:
Text should move based on the percentage of the margins.

Reproducible in:
2019.1.0a13, 2018.3.0a11, 2018.3.0b11

Working Fine in:
2018.3.0a10

Environment:
Windows and Mac.