Support getOccurrences for modifier keywords.
A few touch-ups to the code.
Merge branch 'master' into getOccsForModifiers
Added 'Constructor' to 'isDeclaration' predicate.
Look through constructor parameters if acc. modifier.
Account for variable statements, as they are not declarations.
Added a few tests.
Merge branch 'master' into getOccsForModifiers
Catch modifiers in sourcefiles.
Added more tests.
Fixed comment.
Merge branch 'master' into getOccsForModifiers
Merge pull request #1098 from Microsoft/getOccsForModifiers

Support getOccurrences for modifier keywords.