add pathops tight bounds; conform path ops' gyp to unit tests

src/pathops/SkPathOpsTightBounds.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "SkOpEdgeBuilder.h"
+#include "SkPathOpsCommon.h"
+
+bool TightBounds(const SkPath& path, SkRect* result) {
+    // turn path into list of segments
+    SkTArray<SkOpContour> contours;
+    SkOpEdgeBuilder builder(path, contours);
+    if (!builder.finish()) {
+        return false;
+    }
+    SkTArray<SkOpContour*, true> contourList;
+    MakeContourList(contours, contourList, false, false);
+    SkOpContour** currentPtr = contourList.begin();
+    result->setEmpty();
+    if (!currentPtr) {
+        return true;
+    }
+    SkOpContour** listEnd = contourList.end();
+    SkOpContour* current = *currentPtr++;
+    SkPathOpsBounds bounds = current->bounds();
+    while (currentPtr != listEnd) {
+        current = *currentPtr++;
+        bounds.add(current->bounds());
+    }
+    *result = bounds;
+    return true;
+}