
Fix XSS in goog.History demo page.

Fortunately, it doesn't look like anyone copied the demo page, but it should be xss-free in case someone does in the future.

R=nnaze
DELTA=4  (0 added, 2 deleted, 2 changed)


Revision created by MOE tool push_codebase.
MOE_MIGRATION=958


yamadatomonori/closure-library,yamadatomonori/closure-library,yamadatomonori/closure-library