Most error checking functions in ParseContext used to follow a format
like <property>ErrorCheck. Sometimes this function would check that
the node/value would have <property>, sometimes it would check that
the node/value would not have it, which was confusing. Change most of
these functions to use a lot more descriptive names, which clearly
communicate what they are checking for.

Also includes a bit of refactoring in constructorErrorCheck(), so that
the function only checks for errors rather than also setting the type
of the constructor node.

Also make TType::arraySize unsigned, and return a sanitized size from
checkIsValidArraySize() instead of using an output parameter.

BUG=angleproject:911
TEST=angle_unittests

Change-Id: Id9767b8c79594ad3f782f801ea68eb96df721a31
Reviewed-on: https://chromium-review.googlesource.com/367070Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>