Enable slimming paint by default (for trybots only)

sp/trybots

+#!/bin/sh
+cd `dirname $0`/..
+set -e
+git checkout master
+git pull
+cd ../..
+git checkout master
+git pull
+gclient sync
+cd third_party/WebKit
+
+git checkout EnableSP
+git rebase
+sp/gen-expectations
+git commit -a --amend -m ""
+
+if git branch -D EnableSPCull-temp EnableSPUnderInvalidation-temp; then
+true # Ignore any error
+fi
+
+TRY="git cl try -b linux_blink_rel -b mac_blink_rel -b win_blink_rel"
+
+git checkout -tb EnableSPCull-temp origin/master
+git cherry-pick EnableSP
+git cherry-pick EnableSPCull
+git branch -D EnableSPCull
+git branch -m EnableSPCull
+git cl issue 1135703003
+
+git checkout -tb EnableSPUnderInvalidation-temp origin/master
+git cherry-pick EnableSP
+git cherry-pick EnableSPUnderInvalidation
+git branch -D EnableSPUnderInvalidation
+git branch -m EnableSPUnderInvalidation
+git cl issue 1132203003
+
+git checkout EnableSP
+date | git cl upload
+$TRY
+
+git checkout EnableSPCull
+date | git cl upload
+$TRY
+
+git checkout EnableSPUnderInvalidation
+date | git cl upload
+$TRY -b linux_blink_dbg -b mac_blink_dbg -b win_blink_dbg