JBIDE-13367 NullPointerException in FaceletPageContextImpl.getExternalVars

Completion proposal computers should check if file can be found
by the available document. If not, log illegal state error,
but content assist should not crush.
JBIDE-13380 org.jboss.tools.jst.css.test.jbide.InputFractionalValueTest_JBIDE4790 test failure against Eclipse 4.3.0.M4

make this test negative(after wtp fix test will fail and we will correct it)
JBIDE-13400 - PageContextFactory.ExtendedLinkElementAdapter is leaked