Clean up some random includes in core/svg/ and core/rendering/svg/

Mostly dropping unused headers. Use a more specific include in
SVGGradientElement.cpp.

Review URL: https://codereview.chromium.org/888863002

git-svn-id: svn://svn.chromium.org/blink/trunk@189266 bbb929c8-8fbe-4397-9dbb-9b2b20218538
8 files changed
tree: a4d0ce2a27b9cc743b3a28800017ac4e408f58f6
  1. third_party/