Add SkDashMeasure.h (name up for bikeshedding) which takes a dashinfo

experimental/curve_dash_measure/SkDashMeasure.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkDashMeasure_DEFINED
+#define SkDashMeasure_DEFINED
+
+#include "SkPath.h"
+#include "SkPathEffect.h"
+
+static inline bool dashIsOn(int32_t index) {
+    return !(index % 2);
+}
+
+void getDashedPath(const SkPath& path,
+                            const struct SkPathEffect::DashInfo& dashInfo,
+                            SkPath* dst);
+
+#endif  // SkDashMeasure_DEFINED