Bug 1676974 - [devtools] Remove unused protocol/utils.js method() helper r=ochameau

Current implementation
```lang=javascript
exports.method = function(fn, spec = {}) {
  fn._methodSpec = Object.freeze(spec);
  if (spec.request) {
    Object.freeze(spec.request);
  }
  if (spec.response) {
    Object.freeze(spec.response);
  }
  return fn;
};
```
https://searchfox.org/mozilla-central/rev/5a1a34953a26117f3be1a00db20c8bbdc03273d6/devtools/shared/protocol/utils.js#70-79

The helper method() in protocol/utils.js is only called from two methods:
- actorBridge (never used in the codebase)
- actorBridgeWithSpec (used by a few actors)

actorBridgeWithSpec doesn't pass the second argument, so in practice, this method could be reduced to:
```lang=javascript
exports.method = function(fn) {
  fn._methodSpec = Object.freeze({});
  return fn;
};
```

`_methodSpec` is only mentioned in one other spot: https://searchfox.org/mozilla-central/rev/5a1a34953a26117f3be1a00db20c8bbdc03273d6/devtools/shared/protocol/Actor/generateActorSpec.js#27-40

But based on our coverage tooling, we never actually have a `_methodSpec` when we run this code: https://coverage.moz.tools/#view=file&revision=latest&path=devtools/shared/protocol/Actor/generateActorSpec.js

To hit it, we would have to call `generateActorSpec` directly with an actor where we used `actorBridgeWithSpec`. But we never do that, we only use it with plain JS objects in the devtools/shared/specs folder.

Consequently, this helper can be removed.

Differential Revision: https://phabricator.services.mozilla.com/D96935

devtools/server/actors/common.js

@@ -4,8 +4,6 @@
 
 "use strict";
 
-const { method } = require("devtools/shared/protocol");
-
 /**
  * A SourceLocation represents a location in a source.
  *
@@ -106,28 +104,13 @@ function expectState(expectedState, methodFunc, activity) {
 exports.expectState = expectState;
 
 /**
- * Proxies a call from an actor to an underlying module, stored
- * as `bridge` on the actor. This allows a module to be defined in one
- * place, usable by other modules/actors on the server, but a separate
- * module defining the actor/RDP definition.
- *
- * @see Framerate implementation: devtools/server/performance/framerate.js
- * @see Framerate actor definition: devtools/server/actors/framerate.js
- */
-function actorBridge(methodName, definition = {}) {
-  return method(function() {
-    return this.bridge[methodName].apply(this.bridge, arguments);
-  }, definition);
-}
-exports.actorBridge = actorBridge;
-
-/**
- * Like `actorBridge`, but without a spec definition, for when the actor is
- * created with `ActorClassWithSpec` rather than vanilla `ActorClass`.
+ * Autobind method from a `bridge` property set on some actors where the
+ * implementation is delegated to a separate class, and where `bridge` points
+ * to an instance of this class.
  */
 function actorBridgeWithSpec(methodName) {
-  return method(function() {
+  return function() {
     return this.bridge[methodName].apply(this.bridge, arguments);
-  });
+  };
 }
 exports.actorBridgeWithSpec = actorBridgeWithSpec;

devtools/shared/protocol.js

@@ -12,7 +12,6 @@ var {
   getFront,
   createRootFront,
 } = require("devtools/shared/protocol/types");
-var { method } = require("devtools/shared/protocol/utils");
 var { Front } = require("devtools/shared/protocol/Front");
 var {
   FrontClassWithSpec,
@@ -36,4 +35,3 @@ exports.RetVal = RetVal;
 exports.registerFront = registerFront;
 exports.getFront = getFront;
 exports.createRootFront = createRootFront;
-exports.method = method;

devtools/shared/protocol/Actor/generateActorSpec.js

@@ -17,28 +17,6 @@ var generateActorSpec = function(actorDesc) {
     methods: [],
   };
 
-  // Find method and form specifications attached to properties.
-  for (const name of Object.getOwnPropertyNames(actorDesc)) {
-    const desc = Object.getOwnPropertyDescriptor(actorDesc, name);
-    if (!desc.value) {
-      continue;
-    }
-
-    if (desc.value._methodSpec) {
-      const methodSpec = desc.value._methodSpec;
-      const spec = {};
-      spec.name = methodSpec.name || name;
-      spec.request = new Request(
-        Object.assign({ type: spec.name }, methodSpec.request || undefined)
-      );
-      spec.response = new Response(methodSpec.response || undefined);
-      spec.release = methodSpec.release;
-      spec.oneway = methodSpec.oneway;
-
-      actorSpec.methods.push(spec);
-    }
-  }
-
   // Find additional method specifications
   if (actorDesc.methods) {
     for (const name in actorDesc.methods) {

devtools/shared/protocol/utils.js

@@ -55,25 +55,3 @@ function getPath(obj, path) {
   return obj;
 }
 exports.getPath = getPath;
-
-/**
- * Tags a prtotype method as an actor method implementation.
- *
- * @param function fn
- *    The implementation function, will be returned.
- * @param spec
- *    The method specification, with the following (optional) properties:
- *      request (object): a request template.
- *      response (object): a response template.
- *      oneway (bool): 'true' if no response should be sent.
- */
-exports.method = function(fn, spec = {}) {
-  fn._methodSpec = Object.freeze(spec);
-  if (spec.request) {
-    Object.freeze(spec.request);
-  }
-  if (spec.response) {
-    Object.freeze(spec.response);
-  }
-  return fn;
-};