CSS Shapes Level 1 (CR) only contains shape-outside. We are focusing our efforts on finalizing
the implementation of shape-outside, it's worth to remove shape-inside code at this point for now.

A list of reasons for the removal:

- Shape-inside is only part of Shapes Level 2, which needs to be improved on some topics.
- Shape-inside is lack of new shapes support (e.g. inset).
- Deprecated shapes are removed from the code (e.g. rectangle), which affects shape-inside.
- The current shape-inside code spreads across the layout code.
- The current shape-inside implementation is experimental in some areas, and the partially implemented code can have security implications.
- Removal of shape-inside opens possibilities for code complexity and performance optimizations for shape-outside. (e.g. simpler geometry code) 

BUG=356778

Review URL: https://codereview.chromium.org/209443007

git-svn-id: svn://svn.chromium.org/blink/trunk@170260 bbb929c8-8fbe-4397-9dbb-9b2b20218538