Make plugin elements return false from canStartSelection.

third_party/WebKit/LayoutTests/editing/selection/readonly-disabled-text-selection.html

Index: third_party/WebKit/LayoutTests/editing/selection/readonly-disabled-text-selection.html
diff --git a/third_party/WebKit/LayoutTests/editing/selection/readonly-disabled-text-selection.html b/third_party/WebKit/LayoutTests/editing/selection/readonly-disabled-text-selection.html
index 805c5bd8c2a3da9e528a31d6ad2d9a5783d7cc13..4193d43822c4b42646891232a1a2085777a0c25f 100644
--- a/third_party/WebKit/LayoutTests/editing/selection/readonly-disabled-text-selection.html
+++ b/third_party/WebKit/LayoutTests/editing/selection/readonly-disabled-text-selection.html
@@ -29,10 +29,9 @@ onload = function() {
 function doLongPressOnElement(elementId) {
     var element = document.getElementById(elementId);
     var bounds = element.getBoundingClientRect();
-    var middleX = (bounds.left + bounds.right) / 2;
-    var middleY = (bounds.top + bounds.bottom) / 2;
-    // Touch directly in the center of the element.
-    window.eventSender.gestureLongPress(middleX, middleY);
+    var x = bounds.left + 5;
+    var y = bounds.top + 5;
+    window.eventSender.gestureLongPress(x, y);
     shouldBeEqualToString('window.getSelection().toString()', element.value);
 }
 </script>