[Bug] Inline toolbar is not centred on initial text selection for all blocks.

**Description of Bug:**
When you select the text content of any block with a double click on a new page load, for the first time, the iniline toolbar is not properly centred below the text.
This behaviour is recorded on every new page load as well.

**Steps to reproduce:**
1. Open Editor.js.
2. Double click on any blocks text content for the very first time.

For different blocks the alignment is changing every time.

**Expected behaviour:**

**In the images, I have only showed a few blocks but the problem exists with all blocks which show any textual form of content.**