refactor _stringLocationOffset to property in DTCoreTextLayoutLine
advance glyphRun.stringRange by _line.offstringLocationOffsetset
Lower mem and faster CSS cascading. Fixes #555 and #553. New test took 16.85s before and 0.033s after.
Merge pull request #559 from amro/css_memory_perf_fix

Lower mem and faster CSS cascading. Fixes #555 and #553.
Fix font-size inheritance and cascade both being applied, which caused font-sizes to be doubled in some cases
Merge pull request #560 from amro/fix_incorrect_fontsize_inheritance

Fix font-size inheritance and cascade both being applied,
Add single selector cascade and test
remove renamed method -- left it in accidentally while testing
Merge pull request #564 from amro/add_single_class_cascade

Add single class cascade
Fix substring selectors being matched when cascading
Merge pull request #565 from amro/fix_substring_selector_cascade

Fix substring selectors being matched when cascading
Merge branch 'kybook' into develop