Use float instead of double to increase spot shadow perf

This is helping spot shadow for 15%-20% increase.
With the new algorithm, we are less sensitive to the floating point error.

b/16712006

Change-Id: Ie30a6ce01e73d56054a0cf65a84549454339a7fd
diff --git a/libs/hwui/SpotShadow.h b/libs/hwui/SpotShadow.h
index 23fdca9..6fa2028f 100644
--- a/libs/hwui/SpotShadow.h
+++ b/libs/hwui/SpotShadow.h
@@ -35,8 +35,6 @@
 
     static float projectCasterToOutline(Vector2& outline,
             const Vector3& lightCenter, const Vector3& polyVertex);
-    static int calculateOccludedUmbra(const Vector2* umbra, int umbraLength,
-            const Vector3* poly, int polyLength, Vector2* occludedUmbra);
 
     static int setupAngleList(VertexAngleData* angleDataList,
             int polyLength, const Vector2* polygon, const Vector2& centroid,
@@ -81,8 +79,7 @@
 
     static void xsort(Vector2* points, int pointsLength);
     static int hull(Vector2* points, int pointsLength, Vector2* retPoly);
-    static bool ccw(double ax, double ay, double bx, double by, double cx, double cy);
-    static int intersection(const Vector2* poly1, int poly1length, Vector2* poly2, int poly2length);
+    static bool ccw(float ax, float ay, float bx, float by, float cx, float cy);
     static void sort(Vector2* poly, int polyLength, const Vector2& center);
 
     static void swap(Vector2* points, int i, int j);
@@ -92,8 +89,6 @@
     static bool testPointInsidePolygon(const Vector2 testPoint, const Vector2* poly, int len);
     static void makeClockwise(Vector2* polygon, int len);
     static void reverse(Vector2* polygon, int len);
-    static inline bool lineIntersection(double x1, double y1, double x2, double y2,
-            double x3, double y3, double x4, double y4, Vector2& ret);
 
     static void generateTriangleStrip(bool isCasterOpaque, float shadowStrengthScale,
             Vector2* penumbra, int penumbraLength, Vector2* umbra, int umbraLength,