Bug 1651901 - Disable optimizations in dom/bindings/test. r=froydnj

Differential Revision: https://phabricator.services.mozilla.com/D83033

dom/bindings/test/moz.build

@@ -64,3 +64,10 @@ if CONFIG['MOZ_DEBUG']:
     ]
 
     XPIDL_MODULE = 'dom_bindings_test'
+
+# Because we don't actually link this code anywhere, we don't care about
+# their optimization level, so don't waste time on optimization.
+if CONFIG['CXX_TYPE'] == 'clang-cl':
+    CXXFLAGS += ['-Od']
+else:
+    CXXFLAGS += ['-O0']