[inspector] introduced Debugger.scheduleStepIntoAsync

src/inspector/inspector_protocol_config.json

 {
     "protocol": {
         "path": "js_protocol.json",
         "package": "src/inspector/protocol",
         "output": "protocol",
         "namespace": ["v8_inspector", "protocol"],
         "options": [
             {
                 "domain": "Schema",
                 "exported": ["Domain"]
             },
             {
                 "domain": "Runtime",
                 "async": ["evaluate", "awaitPromise", "callFunctionOn", "runScript"],
                 "exported": ["StackTrace", "RemoteObject"]
             },
             {
                 "domain": "Debugger",
+                "async": [ "scheduleStepIntoAsync" ],
                 "exported": ["SearchMatch", "paused.reason"]
             },
             {
                 "domain": "Console"
             },
             {
                 "domain": "Profiler"
             },
             {
                 "domain": "HeapProfiler"
@@ skipping 10 matching lines @@
         "to_string_out": "StringBufferImpl::adopt(%s)",
         "export_macro": "V8_EXPORT"
     },
 
     "lib": {
         "package": "src/inspector/protocol",
         "output": "protocol",
         "string_header": "src/inspector/string-util.h"
     }
 }