Test top-level Document JS properties.

Along the way, I rename some functions in pdfium_test.cc to
match the style guide's FunctionName() syntax, adding
"Example" to make them obviously different from the PDF
internal code with similar name fragments.

The purpose is to at least have some coverage for the
setter/getter macros from JS_Define.h


Review URL: https://codereview.chromium.org/928573002
3 files changed