IWYU: 'core' target, files starting A-C.

TBR=reed@google.com
Verbal lgtm, does not change API.

Committed: https://skia.googlesource.com/skia/+/7403d87db8e43d4c2b5b25ac22a0ebc22bd09d69

Review URL: https://codereview.chromium.org/1265033002
diff --git a/tests/ClipCubicTest.cpp b/tests/ClipCubicTest.cpp
index 31b38f2..0970b83 100644
--- a/tests/ClipCubicTest.cpp
+++ b/tests/ClipCubicTest.cpp
@@ -9,6 +9,7 @@
 #include "SkCubicClipper.h"
 #include "SkGeometry.h"
 #include "SkPaint.h"
+#include "SkPath.h"
 #include "Test.h"
 
 // Currently the supersampler blitter uses int16_t for its index into an array