Bug 907789 - part 2 - use mozbuild.makeutil to write webidl file lists; r=gps

python/mozbuild/mozbuild/backend/recursivemake.py

@@ -588,9 +588,11 @@ class RecursiveMakeBackend(CommonBackend):
         webidls = FileAvoidWrite(os.path.join(self.environment.topobjdir,
               'dom', 'bindings', 'webidlsrcs.mk'))
 
+        mk = mozmakeutil.Makefile()
+
         def write_var(variable, sources):
             files = [os.path.basename(f) for f in sorted(sources)]
-            webidls.write('%s += %s\n' % (variable, ' '.join(files)))
+            mk.add_statement('%s += %s\n' % (variable, ' '.join(files)))
         write_var('webidl_files', self._webidl_sources)
         write_var('generated_events_webidl_files', self._generated_events_webidl_sources)
         write_var('test_webidl_files', self._test_webidl_sources)
@@ -598,6 +600,8 @@ class RecursiveMakeBackend(CommonBackend):
         write_var('generated_webidl_files', self._generated_webidl_sources)
         write_var('preprocessed_webidl_files', self._preprocessed_webidl_sources)
 
+        mk.dump(webidls)
+
         self._update_from_avoid_write(webidls.close())
         self.summary.managed_count += 1