b=1068964 Bump GTK required version to 2.18.0 r=karlt

Now that Seamonkey is building with CentOS 6
we can bump the gtk version ready for some code tidy ups.

--HG--
extra : transplant_source : q%B0%27%5By%171%F2%21%04Q%B4%07s%0A%9C%BC%19%3C%8B
b=1068964 Remove gtk_check_version for GTK 2 r=karlt

Remove gtk_check_version() checks for GTK 2 as the minimum
version now covers all cases

--HG--
extra : transplant_source : Z%F4%8A2%B1a%D4%16%3B%C1%9F%92b%92%15%3E%AB%9Cg%81
b=1068964 Cleanup GTK print includes r=karlt

--HG--
extra : transplant_source : %18%ED%1B%24%9C%AB%FDA%F8%BE%A3%85%92h%F1%B0%FF%92D%8D
b=1068964 Remove GTK_CHECK_VERSION for GTK 2 r=karlt

Remove all GTK_CHECK_VERSION checks for GTK 2 as the minimum
version now covers all cases

--HG--
extra : transplant_source : %CE%3A%BC%CCm%F3EO%CA%15Z%B9%90%3C%14j%A0%16%851
b=1000044 use direct resampler for 16->44.1k r=jmspeex

This also changes the HUGEMEM test to be independent of quality.
|oversample| has a maximum value of 32, so we know that the interpolating
resampler will use less memory when st->den_rate > 441.

--HG--
extra : transplant_source : vl%C1d%A5%FB%3Cd%FBC%86%FD%26%EC%FB%C0%5C%26%7D%8C
b=1069113 explicitly unset media.mediasource.enabled when testing disabling of MediaSource r=kinetik

so that web platform tests can be run with MediaSource enabled.

--HG--
extra : transplant_source : %C9%01%A22%DF%8C%89%CF%7E6%0E%FCR%EE%0E%BE%15%B1%D2%92
b=1066467 disable MediaSource tests that are unstable or interact badly with other tests r=kinetik

--HG--
extra : transplant_source : %0B%14%3F%12w%A6%A2%C9%0E%7Eu%7E%83%D8%B3%C3%D7l%F79