This test checks that the fallback font is used for layout while a webfont is loading.

Target:
A text to be measured.
A text to be measured.
A text to be measured.
A text to be measured.
Reference:
A text to be measured.
A text to be measured.
A text to be measured.
A text to be measured.
arial
PASS: The width of target text and reference text is the same.
serif
PASS: The width of target text and reference text is the same.
default
PASS: The width of target text and reference text is the same.