added hit detection for symbol edges to canvas renderer with unit tests

Added unit tests for hit detection on invisible canvas layer

simplified unit test for hit detection on invisible canvas

tests/Renderer/Canvas.html

@@ -304,6 +304,17 @@
             ),
             new OpenLayers.Feature.Vector(
                 OpenLayers.Geometry.fromWKT("POLYGON((100 -25, 150 -25, 150 25, 100 25, 100 -25), (120 -5, 130 -5, 130 5, 120 5, 120 -5))")
+            ),
+            new OpenLayers.Feature.Vector(
+                new OpenLayers.Geometry.Point(80, 0), {}, {
+                    graphicName: "square",
+                    pointRadius: 5,
+                    strokeWidth: 3,
+                    fillColor: "red",
+                    fillOpacity: 0.5,
+                    strokeColor: "blue",
+                    strokeOpacity: 0.75
+                } 
             )
         ]);
         
@@ -327,6 +338,12 @@
             msg: "inside polygon hole", x: 125, y: 0, id: null
         }, {
             msg: "outside polygon", x: 155, y: 0, id: null
+        }, {
+            msg: "inside symbol", x: 80, y: 0, id: layer.features[3].id
+        }, {
+            msg: "outside symbol interior, inside symbol edge", x: 86, y: 6, id: layer.features[3].id
+        }, {
+            msg: "outside symbol", x: 90, y: 0, id: null
         }];
 
         function px(x, y) {