Convert editing/inserting/insert-at-end-0[12].html to use w3c test harness
This patch converts "editing/inserting/insert-at-end-0[12].html" to use w3c test
harness to simplify test script, and consolidates into "insert_at_end.html"
since these scripts use similar sample, for improving code health.
BUG=n/a
TEST=n/a; no behavior changes
Committed:
https://crrev.com/6e49adc69ffc520e32ee9ee9fe2be2d24fd2107c
Cr-Commit-Position: refs/heads/master@{#418820}