Remove references to inherited_data_ in ComputedStyle.

To allow changes to where fields are stored, ComputedStyle code should
not refer directly to a group, as that code will break when we change
groups. This patch removes references to inherited_data_ in ComputedStyle,
replacing with generated or handwritten getters. This patch does not
remove references within diffing functions as those will soon be
generated.

BUG=710938

Review-Url: https://codereview.chromium.org/2886293004
Cr-Commit-Position: refs/heads/master@{#473433}
2 files changed