Move more data to .data.rel.ro section

Move CoreException struct and webkitPrefix/bothPrefixes/unprefixed arrays to
from .data section to .data.rel.ro by marking them as const. This data can
now possibly be shared by separate instances of the library on Android, thus
saving RAM.

BUG=249746

Review URL: https://codereview.chromium.org/45803002

git-svn-id: svn://svn.chromium.org/blink/trunk@160680 bbb929c8-8fbe-4397-9dbb-9b2b20218538