DevTools: [SSP] update ranges for all section in sidebar pane

There is a bug due to which source ranges in inherited styles sections
and pseudo elements style sections are not updated on the front-end
as the editing happens. This patch fixes it.

BUG=430129
R=vsevik

Review URL: https://codereview.chromium.org/698113006

git-svn-id: svn://svn.chromium.org/blink/trunk@184861 bbb929c8-8fbe-4397-9dbb-9b2b20218538