Support Git in pub global activate.

sdk/lib/_internal/pub/lib/src/command/global_activate.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library pub.command.global_activate;
 
 import 'dart:async';
 
 import '../command.dart';
 import '../utils.dart';
 import '../version.dart';
 
 /// Handles the `global activate` pub command.
 class GlobalActivateCommand extends PubCommand {
   String get description => "Make a package's executables globally available.";
   String get usage => "pub global activate <package...>";
   bool get takesArguments => true;
 
   GlobalActivateCommand() {
     commandParser.addOption("source",
         abbr: "s",
         help: "The source used to find the package.",
-        allowed: ["hosted", "path"],
+        allowed: ["git", "hosted", "path"],
         defaultsTo: "hosted");
   }
 
   Future onRun() {
     var args = commandOptions.rest;
 
     readArg([String error]) {
       if (args.isEmpty) usageError(error);
       var arg = args.first;
       args = args.skip(1);
       return arg;
     }
 
     validateNoExtraArgs() {
       if (args.isEmpty) return;
       var unexpected = args.map((arg) => '"$arg"');
       var arguments = pluralize("argument", unexpected.length);
       usageError("Unexpected $arguments ${toSentence(unexpected)}.");
     }
 
-    var package = readArg("No package to activate given.");
+    switch (commandOptions["source"]) {
+      case "git":
+        var repo = readArg("No Git repository given.");
+        // TODO(rnystrom): Allow passing in a Git ref too.
+        validateNoExtraArgs();
+        return globals.activateGit(repo);
 
-    switch (commandOptions["source"]) {
       case "hosted":
+        var package = readArg("No package to activate given.");
+
         // Parse the version constraint, if there is one.
         var constraint = VersionConstraint.any;
         if (args.isNotEmpty) {
           try {
             constraint = new VersionConstraint.parse(readArg());
           } on FormatException catch (error) {
             usageError(error.message);
           }
         }
 
         validateNoExtraArgs();
         return globals.activateHosted(package, constraint);
 
       case "path":
+        var path = readArg("No package to activate given.");
         validateNoExtraArgs();
-        return globals.activatePath(package);
+        return globals.activatePath(path);
     }
 
     throw "unreachable";
   }
 }