Description:
Grid component doesn't render when the values in CellSize/CellGap are changed

Steps to Reproduce:
1. Create a New Project
2. In Hierarchy, right click > 2D Objects > Tilemap
3. Change the values of "Cell size" OR "Cell Gap".

Note :
The values differ based on different aspect ratios. Cell Gap X value 0.4 is common across all aspect ratios. Other sample values are attached in the screenshot below at which the Grid doesn't render.

Expected Result : Grid should be rendered properly in the Scene view.

Actual Result : Grid is not being rendered.

Environment:
- Appears on both platforms (Mac and Windows).

Frequency:
- Appears Always.

Reproduces on: 2018.1.0a7, 2018.1.0a5, 2018.1.0a2, 2018.1.0a1, 2017.3.0f2, 2017.3.0f1, 2017.2.0f3