Add missing idl attribute entries for lazyLoad attribute.

In previous CLs, support for the lazyLoad attribute was added, but the
corresponding idl attribute entries were mistakely forgotten. This CL
adds those attribute entries, making it possible to detect if the
browser supports native lazy loading from JavaScript.

Spec: https://github.com/whatwg/html/pull/3752
ChromeStatus entry: https://www.chromestatus.com/feature/5645767347798016
Intent to implement: https://groups.google.com/a/chromium.org/d/msg/blink-dev/czmmZUd4Vww/1-H6j-zdAwAJ

Bug: 913162
Change-Id: Ib801c376ac70bf14eb2779e1642409f9cf03a95d
Reviewed-on: https://chromium-review.googlesource.com/c/1372534
Commit-Queue: Scott Little <sclittle@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622203}
2 files changed