[Bug Report] Time picker doesn't visually select the part being edited via directional keys

[mattheyan]

Element UI version

2.11.1

OS/Browsers version

Windows 10 / Google Chrome 75

Vue version

2.6.10

Reproduction Link

https://codepen.io/mattheyan/pen/gVxMbM

Steps to reproduce

1. Click into the text input so that one of the time parts (hours, minutes, seconds) is selected
2. Press the up or down keys to increase or decrease the value

What is Expected?

The value show increase or decrease, and that part of the time should remain selected

What is actually happening?

The value is increased or decreased, but the text selection disappears and the cursor moves to the end of the input.

[mattheyan]

I am able to implement a fix and will submit a PR for your review

[mattheyan]

Adding this at the end of the scrollDown method fixes the problem.

this.$nextTick(() => this.emitSelectRange(this.currentScrollbar));