Add cropped-then-expanded test cases to blur_image_filter tests.
Add cropped-then-expanded test cases to blur_image_filter tests.

These are benches similar to the imagefilterscropexpand GM: an
input filter is cropped to a smaller size, then the blur is re-expanded
out to a larger size.

BUG=skbug:4502

Review URL: https://codereview.chromium.org/1412373004

HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,tmpvar/skia.cc,qrealka/skia-hc,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,rubenvb/skia,tmpvar/skia.cc,tmpvar/skia.cc,Hikari-no-Tenshi/android_external_skia,tmpvar/skia.cc,rubenvb/skia,google/skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,google/skia,HalCanary/skia-hc,tmpvar/skia.cc,qrealka/skia-hc,HalCanary/skia-hc,aosp-mirror/platform_external_skia,HalCanary/skia-hc,rubenvb/skia,google/skia,google/skia,qrealka/skia-hc,google/skia,aosp-mirror/platform_external_skia,google/skia,qrealka/skia-hc,google/skia,tmpvar/skia.cc,aosp-mirror/platform_external_skia,tmpvar/skia.cc,qrealka/skia-hc,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,rubenvb/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,rubenvb/skia,tmpvar/skia.cc,HalCanary/skia-hc,aosp-mirror/platform_external_skia,rubenvb/skia,qrealka/skia-hc,Hikari-no-Tenshi/android_external_skia,tmpvar/skia.cc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,aosp-mirror/platform_external_skia,rubenvb/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,google/skia,qrealka/skia-hc,qrealka/skia-hc,google/skia,Hikari-no-Tenshi/android_external_skia