Move Dashing filterPath to a dashing utils file

src/utils/SkDashPathPriv.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkDashPathPriv_DEFINED
+#define SkDashPathPriv_DEFINED
+
+#include "SkPathEffect.h"
+
+namespace SkDashPath {
+    /*
+     * Calculates the initialDashLength, initialDashIndex, and intervalLength based on the
+     * inputed phase and intervals. If adjustedPhase is passed in, then the phase will be
+     * adjusted to be between 0 and intervalLength. The result will be stored in adjustedPhase.
+     * If adjustedPhase is NULL then it is assumed phase is already between 0 and intervalLength
+     */
+    void CalcDashParameters(SkScalar phase, const SkScalar intervals[], int32_t count,
+                            SkScalar* initialDashLength, int32_t* initialDashIndex,
+                            SkScalar* intervalLength, SkScalar* adjustedPhase = NULL);
+
+    bool FilterDashPath(SkPath* dst, const SkPath& src, SkStrokeRec*, const SkRect*,
+                        const SkScalar aIntervals[], int32_t count, SkScalar initialDashLength,
+                        int32_t initialDashIndex, SkScalar intervalLength);
+    
+    bool FilterDashPath(SkPath* dst, const SkPath& src, SkStrokeRec*, const SkRect*,
+                        const SkPathEffect::DashInfo& info);
+}
+
+#endif