Trailing space characters in an editable text node are sometimes ignored (as normal for HTML) and sometimes rendered (as if in CSS "white-space: pre").

Repro:

1. Go to: https://output.jsbin.com/qepatof
2. Click in the red box to focus it.
3. Move cursor to end of the text by holding right arrow key.
4. Type "x" once.

Expected result:
The last word in the box should be "xxxx".

Actual result:
The "x" is a word by itself.

The green boxes have what I believe is the correct behavior.  Note that all three boxes have the same DOM content; only their sizes are different.  The whitespace interpretation depends on the line wrapping, which is very weird.

Setting "line-break: normal" on the div corrects the problem.  This implicates the "-webkit-line-break: after-white-space" style that is added in HTMLElement::CollectStyleForPresentationAttribute.  See also issue 427135 which aims to remove this.

Discovered while looking at editing/inserting/typing-at-end-of-line.html.  There shouldn't be two spaces before "have", but there have been since http://crrev.com/9638d384.