Steps to reproduce:
1. Open project attached and Open scene "Test". In "Hierarchy" window notice "InputField" component.
2. Click the "Play" button.
3. In "Game" window click on input field, which suggests to "Enter text...".
4. Enter leading decimal point and any number. For example, ".5". Everything should work.
5. Then, in "Game" window click outside of Input Field's region.
6. Again click on Input Field and try to enter leading decimal point.
7. Notice that text field is selected, but cannot be changed by entering a leading decimal point.
8. However, try to enter any number and it works as intended.

Expected result:
User should be able to reenter leading decimal point.

Reproduced on:
5.1.0f3, 5.2.4f1, 5.3.2f1, 5.3.4f1, 5.4.0b11

Workaround: before reentering decimal point, delete value of the input field.