DevTools: add a mega test for console format before devtools startup

With the new test framework, all of the console messages in the regular
console tests are displaying object preview. This closes the gap in coverage
by testing the formatting of console messages fired before DevTools is open
(these messages don't have object preview.)

Note: This is a combination of console-format.js, console-format-es6.js,
console-format-table.js, and console-format-collections.js. (Which helps
explain why this test is slow).

Bug: 667560
Change-Id: Ibe5317570030c8964486121fddc1f5af29d387d2
Reviewed-on: https://chromium-review.googlesource.com/691042Reviewed-by: Will Chen <chenwilliam@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Will Chen <chenwilliam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505433}

third_party/WebKit/LayoutTests/SlowTests

@@ -137,6 +137,7 @@ crbug.com/246190 [ Release ] http/tests/devtools/indexeddb/ [ Slow ]
 crbug.com/246190 [ Release ] virtual/mojo-loading/http/tests/devtools/indexeddb/ [ Slow ]
 crbug.com/451577 [ Mac ] http/tests/devtools/extensions/extensions-sidebar.html [ Slow ]
 crbug.com/451577 [ Mac ] http/tests/devtools/extensions/extensions-events.html [ Slow ]
+crbug.com/667560 http/tests/devtools/startup/console/console-format-startup.html [ Slow ]
 
 # Random slow tests
 webkit.org/b/90488 [ Release ] http/tests/devtools/compiler-source-mapping-debug.html [ Slow ]