Fix typo in LayoutTests/editing/execCommand/apply-style-iframe-crash.html

This patch fixes typo in LayoutTests/editing/execCommand/apply-style-iframe-crash.html

BUG=n/a
TEST=LayoutTests/editing/execCommand/apply-style-iframe-crash.html

Review URL: https://codereview.chromium.org/73873002

git-svn-id: svn://svn.chromium.org/blink/trunk@162130 bbb929c8-8fbe-4397-9dbb-9b2b20218538