19787 [web] Improve perf and code size of line breaker (cla: yes, platform-web, waiting for tree to go green)

19846 [web] Cache line break property lookups (cla: yes, platform-web)

19924 [web] Enable canvas measurement by default (cla: yes, platform-web)

20067 [web] Set correct defaults for text in canvas (cla: yes, platform-web)

20208 [web] Include trailing spaces in text box measurements (cla: yes, platform-web)

20276 [web] Implement support for WidgetSpan (aka paragraph placeholders) (cla: yes, platform-web)

20278 [web] Eagerly calculate relevant indices during line break detection (cla: yes, platform-web)