selection: Do not run invalid sub-tests with unselectable Range.

third_party/WebKit/LayoutTests/external/wpt/selection/addRange.js

Index: third_party/WebKit/LayoutTests/external/wpt/selection/addRange.js
diff --git a/third_party/WebKit/LayoutTests/external/wpt/selection/addRange.js b/third_party/WebKit/LayoutTests/external/wpt/selection/addRange.js
index 5b94f86da739f311ce2d65ed59fd6830c0ce3576..855520e538964cade61ee190e5b9a71de84f95cf 100644
--- a/third_party/WebKit/LayoutTests/external/wpt/selection/addRange.js
+++ b/third_party/WebKit/LayoutTests/external/wpt/selection/addRange.js
@@ -1,6 +1,23 @@
 "use strict";
 
 function testAddRange(exception, range, endpoints, qualifier, testName) {
+    if (!isSelectableNode(endpoints[0]) || !isSelectableNode(endpoints[2])) {
+        test(function() {
+            assert_equals(exception, null, "Test setup must not throw exceptions");
+
+            assertSelectionNoChange(function() { selection.addRange(range); });
+            assert_equals(range.startContainer, endpoints[0],
+                "addRange() must not modify the startContainer of the Range it's given");
+            assert_equals(range.startOffset, endpoints[1],
+                "addRange() must not modify the startOffset of the Range it's given");
+            assert_equals(range.endContainer, endpoints[2],
+                "addRange() must not modify the endContainer of the Range it's given");
+            assert_equals(range.endOffset, endpoints[3],
+                "addRange() must not modify the endOffset of the Range it's given");
+        }, testName + ": " + qualifier + " addRange() must do nothing");
+        return;
+    }
+
     test(function() {
         assert_equals(exception, null, "Test setup must not throw exceptions");
 
@@ -176,7 +193,8 @@ function testAddRangeSubSet(startIndex, optionalEndIndex) {
             }
 
             testAddRange(exception, range1, endpoints1, "first", testName);
-            testAddRange(exception, range2, endpoints2, "second", testName);
+            if (selection.rangeCount > 0)
+                testAddRange(exception, range2, endpoints2, "second", testName);
         }
     }
 }