[ts] Typecheck source_frame/ImageView.js with TypeScript
[ts] Typecheck source_frame/ImageView.js with TypeScript

Bug: chromium:1011811
Change-Id: I634abf11694ee26df9ac88e9e8d6e740d070af65
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2497147
Reviewed-by: Simon Zünd <38944668e9e2ca98ccd0275b53370f90fa55c113@chromium.org>
Commit-Queue: Andres Olivares <9d3bededfc9b98cb289557338a8f98e77d597607@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend