Hit test SVG line boxes

third_party/WebKit/LayoutTests/svg/hittest/text-multiple-dx-values.svg

+<svg onload="runTest()" width="500" height="150" viewBox="0 0 1000 300" xmlns="http://www.w3.org/2000/svg">
+    <rect id="background" width="100%" height="100%" fill="blue" />
+    <text id="text" x="10" y="1em" dx="0 50 100">Foo</text>
+    <defs>
+        <style type="text/css">
+        <![CDATA[
+            @font-face {
+                font-family: Ahem;
+                src: url(../../resources/Ahem.ttf);
+            }
+            text {
+                font-family: Ahem;
+                font-size: 40px;
+            }
+        ]]>
+        </style>
+        <script type="text/javascript">
+        <![CDATA[
+            function runTest() {
+                if (window.testRunner)
+                    testRunner.dumpAsText();
+
+                // The point at 15,15 is contained within the text's bounding box.
+                // The point at 30,15 is contained in between the text's character cells
+                // and thus should return the background.
+                var text = document.getElementById("text");
+                var background = document.getElementById("background");
+                if (document.elementFromPoint(15, 15) === text && document.elementFromPoint(35, 15) === background)
+                    text.textContent = "PASS";
+                else
+                    text.textContent = "FAIL";
+            }
+        ]]>
+        </script>
+    </defs>
+</svg>