DevTools: add more logging to console-viewport-selection.html

LayoutTests/inspector/console/console-viewport-selection-expected.txt

 CONSOLE MESSAGE: line 9: Message #0
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 CONSOLE MESSAGE: line 9: Message #4
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 CONSOLE MESSAGE: line 9: Message #8
 CONSOLE MESSAGE: line 9: Message #9
@@ skipping 134 matching lines @@
 CONSOLE MESSAGE: line 9: Message #144
 CONSOLE MESSAGE: line 9: Message #145
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 Tests that console viewport handles selection properly.
 
 
 Running: verifyViewportIsTallEnough
+Viewport contains 13 messages
 
 Running: testSelectionSingleLineText
 Selected text:<<<EOL
 ssage
 EOL
+last visible message index: 75
 
 Running: testReversedSelectionSingleLineText
 Selected text:<<<EOL
 ssage
 EOL
+last visible message index: 75
 
 Running: testSelectionMultiLineText
 Selected text:<<<EOL
 age #73 console-viewport-selection.html:9
 Message #74 console-viewport-selection.html:9
 Message
 EOL
+last visible message index: 76
 
 Running: testSimpleVisibleSelection
 anchor = {item: 72, offset: 6}, head = {item: 77, offset: 6}
 last visible message index: 77
 
 Running: testHalfScrollSelectionUp
 anchor = {item: 72, offset: 6}, head = {item: 77, offset: 6}
 first visible message index: 75
 
 Running: testHalfScrollSelectionDown
@@ skipping 25 matching lines @@
 last visible message index: 76
 
 Running: testShiftClickReversedSelectionOver
 anchor = {item: 76, offset: 6}, head = {item: 10, offset: 0}
 first visible message index: 5
 
 Running: testShiftClickReversedSelectionBelow
 anchor = {item: 76, offset: 6}, head = {item: 140, offset: 0}
 first visible message index: 135