Rename 'composed tree' to 'flat tree' in the layout tests.

third_party/WebKit/LayoutTests/fast/dom/shadow/flat-tree-traversal-expected.txt

 CONSOLE WARNING: Calling Element.createShadowRoot() for an element which already hosts a shadow root is deprecated. See https://www.chromestatus.com/features/4668884095336448 for more details.
 Tests for Composed Shadow DOM Tree Traversal APIs. Can only run within DRT
 
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
 ShadowRoot should be used.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
 
 Traverse in forward.
 #a
 #b
 Traverse in backward.
 #b
 #a
 
 A content element should select light children
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
         #c
         #d
 
 Traverse in forward.
 #a
 #b
 #c
 #d
 Traverse in backward.
 #d
 #c
 #b
 #a
 
 Test for content element selector.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
         #d
 
 Traverse in forward.
 #a
 #b
 #d
 Traverse in backward.
 #d
 #b
 #a
 
 Light children should be selected only at once.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
         #d
         #c
         #e
 
 Traverse in forward.
 #a
 #b
 #d
 #c
 #e
 Traverse in backward.
 #e
 #c
 #d
 #b
 #a
 
 A content element can have fallback elements.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
         #f1
         #f2
 
 Traverse in forward.
 #a
 #b
 #f1
 #f2
 Traverse in backward.
 #f2
 #f1
 #b
 #a
 
 Fallback elements should not be used if a content element selects an element.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
         #c
 
 Traverse in forward.
 #a
 #b
 #c
 Traverse in backward.
 #c
 #b
 #a
 
 Test for traversal, starting with a fallback element which is not used.
-Composed Shadow Tree:
+Flat Tree:
 #f1
         #f2
 
 Traverse in forward.
 #f1
 #f2
 Traverse in backward.
 #f2
 #f1
 
 Next node of [#f1] is [#f2]
 Next node of [#f2] is [null]
 
 Test for Nested ShadowRoots.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
                 #c
                 #e
                 #d
         #f
         #h
         #i
         #g
 
@@ skipping 12 matching lines @@
 #i
 #h
 #f
 #d
 #e
 #c
 #b
 #a
 
 Test for Multiple ShadowRoots.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #d
         #b
         #f
         #c
         #e
 
 Traverse in forward.
 #a
 #d
 #b
 #f
 #c
 #e
 Traverse in backward.
 #e
 #c
 #f
 #b
 #d
 #a
 
 Test for inactive insertion points.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
                 #c
 
 Traverse in forward.
 #a
 #b
 #c
 Traverse in backward.
 #c
 #b
 #a
 
 Test for an orphaned shadow subtree.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #d
 
 Traverse in forward.
 #a
 #d
 Traverse in backward.
 #d
 #a
 
 Test for traversal, starting with a node in an orphaned shadow subtree.
-Composed Shadow Tree:
+Flat Tree:
 #b
         #c
 
 Traverse in forward.
 #b
 #c
 Traverse in backward.
 #c
 #b
 
 Test for a content element which does not select any nodes nor have fallback elements.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
         #c
 
 Traverse in forward.
 #a
 #b
 #c
 Traverse in backward.
 #c
 #b
 #a
 
 Test for a nested insertion point.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
                 #c
 
 Traverse in forward.
 #a
 #b
 #c
 Traverse in backward.
 #c
 #b
 #a
 
 Test for nested insertion points. Some of them are either empty insertion points or inactive insertion points.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
                 #c
                 #d
                 #e
 
 Traverse in forward.
 #a
 #b
 #c
 #d
 #e
 Traverse in backward.
 #e
 #d
 #c
 #b
 #a
 
 Test for a re-projection.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
                 #c
 
 Traverse in forward.
 #a
 #b
 #c
 Traverse in backward.
 #c
 #b
 #a
 
 Test for a content element which is selected by another content element.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
                 #most-inner-child
                 #host-child
 
 Traverse in forward.
 #a
 #b
 #most-inner-child
 #host-child
 Traverse in backward.
 #host-child
 #most-inner-child
 #b
 #a
 
 Test for a reprojection. Content elements should be used in document order.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #host-child1
         #b
                 #host-child2
 
 Traverse in forward.
 #a
 #host-child1
 #b
 #host-child2
 Traverse in backward.
 #host-child2
 #b
 #host-child1
 #a
 
 Test for complex re-projections.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
                 #child-1
                 #d
                         #e
                         #child-2
                         #g
                         #f
                 #h
                 #c
@@ skipping 15 matching lines @@
 #f
 #g
 #child-2
 #e
 #d
 #child-1
 #b
 #a
 
 Test for a shadow insertion point where nothing is distributed.
-Composed Shadow Tree:
+Flat Tree:
 #a
         #b
         #c
 
 Traverse in forward.
 #a
 #b
 #c
 Traverse in backward.
 #c
 #b
 #a
 
 PASS successfullyParsed is true
 
 TEST COMPLETE