use scratch path to save on mallocs in drawAtlas
use scratch path to save on mallocs in drawAtlas

20% savings on drawAtlas with rotated content

Change-Id: I928de590629c9f1ea41e9053041095922cab3efc
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/239917
Reviewed-by: Mike Reed <f5cabf8735907151a446812c9875d6c0c712d847@google.com>
Commit-Queue: Mike Reed <f5cabf8735907151a446812c9875d6c0c712d847@google.com>
Auto-Submit: Mike Reed <f5cabf8735907151a446812c9875d6c0c712d847@google.com>

google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,HalCanary/skia-hc,HalCanary/skia-hc,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,google/skia,google/skia,HalCanary/skia-hc,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,HalCanary/skia-hc