Make paint/invalidation/repaint-across-writing-mode-boundary.html

This patch changes "repaint-across-writing-mode-boundary.html" independent from
platform dependent hit test behavior "move cart to boundary when hit point is
above/below line." for a preparation of enabling EditingNG.

Before this patch, the test simulates to move mouse pointer at little bit right
of selected text in vertical-rl writing mode.

Bug: 707656, 971414
Change-Id: I142e63355dbf0944c84b2b86ca0b2190134f79d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225684
Commit-Queue: Koji Ishii <kojii@chromium.org>
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774463}

third_party/blink/web_tests/paint/invalidation/repaint-across-writing-mode-boundary.html

@@ -4,12 +4,22 @@
 <script src="resources/text-based-repaint.js"></script>
 <script>
 function repaintTest() {
-    if (eventSender) {
-        eventSender.mouseMoveTo(569, 189);
+    const target = document.getElementById('target');
+    const range = new Range();
+    // select "par^agra|ph 1" in target
+    range.setStart(target.firstChild, 8);
+    range.setEnd(target.firstChild, 12);
+    const rect = range.getClientRects()[0];
+    const center = rect.left + rect.width / 2;
+    if (window.eventSender) {
+        eventSender.mouseMoveTo(center, rect.top);
         eventSender.mouseDown();
-        eventSender.mouseMoveTo(569, 189);
-        eventSender.mouseMoveTo(569, 229);
+        eventSender.mouseMoveTo(center, rect.top);
+        eventSender.mouseMoveTo(center, rect.bottom);
         eventSender.mouseUp();
+        const actual = getSelection().toString();
+        if (actual !== range.toString())
+            console.log(`It should be "agra" instead of "${actual}".`);
     }
 }
 </script>
@@ -70,7 +80,7 @@ p {
 
 <div class="lrblock">
 <div class="basic d0"><p>第一段落 paragraph 1</p><p>第二段落 paragraph 2</p></div>
-<div class="basic d1 vert"><p>第一段落 paragraph 1</p><p>第二段落 paragraph 2</p></div>
+<div class="basic d1 vert"><p id="target">第一段落 paragraph 1</p><p>第二段落 paragraph 2</p></div>
 </div>
 
 </body>