Rework requests in execution domain

pkg/analysis_server/lib/src/protocol.dart

Index: pkg/analysis_server/lib/src/protocol.dart
diff --git a/pkg/analysis_server/lib/src/protocol.dart b/pkg/analysis_server/lib/src/protocol.dart
index dfa810cdb1deb06f8617cc37ca9097667b1bb150..10aea74de164a84d68c06ce7869d33014ab7ae57 100644
--- a/pkg/analysis_server/lib/src/protocol.dart
+++ b/pkg/analysis_server/lib/src/protocol.dart
@@ -763,6 +763,18 @@ class Response {
 
   /**
    * Initialize a newly created instance to represent an error condition caused
+   * by a [request] that specifies an execution context whose context root does
+   * not exist.
+   */
+  Response.invalidExecutionContext(Request request, String contextId)
+      : this(
+          request.id,
+          error: new RequestError(
+              RequestErrorCode.INVALID_EXECUTION_CONTEXT,
+              "Invalid execution context: $contextId"));
+
+  /**
+   * Initialize a newly created instance to represent an error condition caused
    * by a [request] that had invalid parameter.  [path] is the path to the
    * invalid parameter, in Javascript notation (e.g. "foo.bar" means that the
    * parameter "foo" contained a key "bar" whose value was the wrong type).
@@ -773,7 +785,7 @@ class Response {
           request.id,
           error: new RequestError(
               RequestErrorCode.INVALID_PARAMETER,
-              "Expected parameter $path to $expectation"));
+              "Invalid parameter '$path'. $expectation."));
 
   /**
    * Initialize a newly created instance to represent an error condition caused
@@ -785,6 +797,17 @@ class Response {
           error: new RequestError(RequestErrorCode.INVALID_REQUEST, 'Invalid request'));
 
   /**
+   * Initialize a newly created instance to represent the
+   * REFACTORING_REQUEST_CANCELLED error condition.
+   */
+  Response.refactoringRequestCancelled(Request request)
+      : this(
+          request.id,
+          error: new RequestError(
+              RequestErrorCode.REFACTORING_REQUEST_CANCELLED,
+              'The `edit.getRefactoring` request was cancelled.'));
+
+  /**
    * Initialize a newly created instance to represent the SERVER_ERROR error
    * condition.
    */
@@ -810,17 +833,6 @@ class Response {
 
   /**
    * Initialize a newly created instance to represent the
-   * REFACTORING_REQUEST_CANCELLED error condition.
-   */
-  Response.refactoringRequestCancelled(Request request)
-      : this(
-          request.id,
-          error: new RequestError(
-              RequestErrorCode.REFACTORING_REQUEST_CANCELLED,
-              'The `edit.getRefactoring` request was cancelled.'));
-
-  /**
-   * Initialize a newly created instance to represent the
    * SORT_MEMBERS_PARSE_ERRORS error condition.
    */
   Response.sortMembersParseErrors(Request request, int numErrors)