Describe the bug

On Android only, when two blocks are going to be merged, deleting a swiped word at the beginning of the second block prevents them from being merge-able.

To Reproduce

1. Deleting Swiped Word

1. Type some words into a paragraph block
2. Move the cursor somewhere to the middle of the text and tap Enter to split the block
3. Add a word by swiping (also test tapping) (if you tap letters instead of swiping the bug does not occur. It occurs with tapping out words as well, but only if you select the entire word and then hit backspace)
4. Delete that word by pressing backspace
5. Press backspace to merge the blocks
6. Observe that the blocks will not merge (nothing happens when you press backspace).

2. Deleting Selected Word

1. Type some words into a paragraph block
2. Tap Enter to create a second paragraph block
3. Type some words into the second paragraph block
4. Delete the first word in the second paragraph block by selecting it and pressing backspace
5. Press backspace again to merge the blocks
6. Observe that the blocks will not merge (nothing happens when you press backspace the second time).

Expected behavior

When two paragraph blocks exist next to each other, pressing backspace at the beginning of the second paragraph block should always merge the two blocks.

Smartphone (please complete the following information):

• Device: Pixel 1
• OS: Android X
• Version Verified during 1.30 release testing (c2a85e0), but this issue was first observed on April 2: Styled text not merged using backspace #1873 (comment)