Version 65.0.3286.0 (Official Build) canary (64-bit)(
Firmware Version Google_Samus.6300.174.0

Chrome does not read document as you type now, but does begin to read the current line when text wraps to the next line, also, Chromevox reads words before they are complete when they contain an apostrophe 

Steps to repro:
# With Chromevox running, and key echo set to word, compose a mail in gmail
# Type a sentence that is long enough to be wrapped to the next line
# Notice that when the word on the first line is too long and is moved to the second line, Chromevox reads it as it is moved.
# Type the word 'that's' and 'don't'
# Notice that Chromevox says 'that' then 's' and 'don' then 't'

Expected: Chromevox will only announce words when user presses space or enter. Consider announcing also  on standard punctuation too.

Actual: Chromevox announces words that are moved to the next line and word fragments that are separated by apostrophe

Fixed in m65.