Follow-up to 4e2e9be6a - Move HeapSnapshot DevTools-only Modules back to DevTools

I am so done with this.

Resolves #316

devtools/shared/heapsnapshot/moz.build

@@ -0,0 +1,15 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    'census-tree-node.js',
+    'CensusUtils.js',
+    'DominatorTreeNode.js',
+    'HeapAnalysesClient.js',
+    'HeapAnalysesWorker.js',
+    'HeapSnapshotFileUtils.js',
+    'shortest-paths.js',
+)

devtools/shared/moz.build

@@ -14,6 +14,7 @@ DIRS += [
     'discovery',
     'fronts',
     'gcli',
+    'heapsnapshot',
     'inspector',
     'jsbeautify',
     'layout',

dom/heapsnapshot/moz.build

@@ -48,16 +48,5 @@ DEFINES['GOOGLE_PROTOBUF_NO_RTTI'] = True
 
 FINAL_LIBRARY = 'xul'
 
-if CONFIG['MOZ_DEVTOOLS_SERVER']:
-    DevToolsModules(
-        'census-tree-node.js',
-        'CensusUtils.js',
-        'DominatorTreeNode.js',
-        'HeapAnalysesClient.js',
-        'HeapAnalysesWorker.js',
-        'HeapSnapshotFileUtils.js',
-        'shortest-paths.js',
-    )
-
 if CONFIG['GNU_CXX']:
     CXXFLAGS += ['-Wno-error=shadow']