Clean up SkPathRef::makeSpace.
Clean up SkPathRef::makeSpace.

Note that this does not clean up the users of this function, which
may themselves be subject to other overflow issues.

BUG=chromium:728936

Change-Id: I3eaa7627c3b6ff49296ea2618a0157dacdc1d9cc
Reviewed-on: https://skia-review.googlesource.com/29121
Commit-Queue: Ben Wagner <53965154ffeecc4a10886eab9259e95965f2979a@google.com>
Reviewed-by: Mike Klein <14574f09dfa9b4e14759b88c3426a495a0e627b0@chromium.org>
Reviewed-by: Ben Wagner <53965154ffeecc4a10886eab9259e95965f2979a@google.com>

aosp-mirror/platform_external_skia,rubenvb/skia,rubenvb/skia,aosp-mirror/platform_external_skia,rubenvb/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,rubenvb/skia,HalCanary/skia-hc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,google/skia,rubenvb/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,google/skia,HalCanary/skia-hc,google/skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,HalCanary/skia-hc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,rubenvb/skia,rubenvb/skia,google/skia,Hikari-no-Tenshi/android_external_skia,google/skia,HalCanary/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia