DevTools: Support asynchronous call stacks on backend.

Source/devtools/protocol.json

Index: Source/devtools/protocol.json
diff --git a/Source/devtools/protocol.json b/Source/devtools/protocol.json
index d88000076485ef407c9d887ff918fed92dcb567d..b3c98f01c5664d9deaafe8437b2dcca132a88169 100644
--- a/Source/devtools/protocol.json
+++ b/Source/devtools/protocol.json
@@ -3339,6 +3339,14 @@
                 ],
                 "hidden": true,
                 "description": "Makes backend skip steps in the sources with names matching given pattern. VM will try leave blacklisted scripts by performing 'step in' several times, finally resorting to 'step out' if unsuccessful."
+            },
+            {
+                "name": "setAsyncCallStackDepth",
+                "parameters": [
+                    { "name": "maxDepth", "type": "integer", "description": "Maximum depth of async call stacks. Setting to <code>0</code> will effectively disable collecting async call stacks (default)." }
+                ],
+                "hidden": true,
+                "description": "Enables or disables async call stacks tracking."
             }
         ],
         "events": [