Add [OverrideBuiltins] to HTMLCollection IDL interface

Add [OverrideBuiltins] to HTMLCollection IDL interface to match the behavior of
NodeList before r166356, which removed NodeList's named getter.

This fixes the performance regression on Dromaeo's dom-query caused by r166263,
which made getElementByTagName() return an HTMLCollection instead of a
NodeList. Iterating over an HTMLCollection was much slower than iterating over
a NodeList and as it turns out, the profiler was telling me that we were
spending ~20% of the time in HTMLCollection's namedPropertyGetter. I compared
NodeList's namedPropertyGetter and HTMLCollection's and noticed that the former
has a lot less branching due to [OverrideBuiltins].

Adding [OverrideBuiltins] to HTMLCollection IDL interface improves Dromaeo's
dom-query score by ~16.5%.

R=haraken, arv
BUG=340325

Review URL: https://codereview.chromium.org/144233008

git-svn-id: svn://svn.chromium.org/blink/trunk@166628 bbb929c8-8fbe-4397-9dbb-9b2b20218538