DevTools: implement release note behind an experiment

third_party/WebKit/Source/devtools/front_end/sdk/ConsoleModel.js

Index: third_party/WebKit/Source/devtools/front_end/sdk/ConsoleModel.js
diff --git a/third_party/WebKit/Source/devtools/front_end/sdk/ConsoleModel.js b/third_party/WebKit/Source/devtools/front_end/sdk/ConsoleModel.js
index e839a2f2be8d006024a0ea38cfe7deec1accba91..3e14545ed1e5e1b2f8fd4b97ebfb4af5ff93d132 100644
--- a/third_party/WebKit/Source/devtools/front_end/sdk/ConsoleModel.js
+++ b/third_party/WebKit/Source/devtools/front_end/sdk/ConsoleModel.js
@@ -484,7 +484,7 @@ SDK.ConsoleMessage.MessageSource = {
   Worker: 'worker',
   Violation: 'violation',
   Intervention: 'intervention',
-  Other: 'other'
+  Other: 'other',

[luoe, 2017/02/11 00:30:54]

nit: commas at the end of the last entry should be consistent.  It looks like
this file excluded them before

 };
 
 /**
@@ -518,7 +518,8 @@ SDK.ConsoleMessage.MessageLevel = {
   Verbose: 'verbose',
   Info: 'info',
   Warning: 'warning',
-  Error: 'error'
+  Error: 'error',
+  Note: 'note',

[luoe, 2017/02/11 00:30:54]

I don't like how making release-notes a ConsoleViewMessage has introduced a note
'level' and 'type', making SDK aware of it.

If we want it viewported, can we try an alternative approach where we make a new
class that implements Console.ConsoleViewportElement, something like
Help.ConsoleHelpMessage?  It would require slight modification to ConsoleView's
itemCount, itemElement, fastHeight, but avoids touching ConsoleViewMessage at
all.

If we know that the help message is always going to be at the top, it could be
similar to the 'N messages hidden by filters' element that isn't viewported.  If
we end up wanting it to always be at the bottom, we can insert it after the
viewport but above the prompt.  wdyt?

 };
 
 /**