Merge branch 'master' into devtools-renable-copy-attr-context-menu-for-firefox

Author: Brian Vaughn

packages/react-devtools-extensions/src/injectGlobalHook.js

@@ -86,11 +86,17 @@ if (sessionStorageGetItem(SESSION_STORAGE_RELOAD_AND_PROFILE_KEY) === 'true') {
   injectCode(rendererCode);
 }
 
-// Inject a `__REACT_DEVTOOLS_GLOBAL_HOOK__` global so that React can detect that the
-// devtools are installed (and skip its suggestion to install the devtools).
-injectCode(
-  ';(' + installHook.toString() + '(window))' + saveNativeValues + detectReact,
-);
+// Inject a __REACT_DEVTOOLS_GLOBAL_HOOK__ global for React to interact with.
+// Only do this for HTML documents though, to avoid e.g. breaking syntax highlighting for XML docs.
+if (document.contentType === 'text/html') {
+  injectCode(
+    ';(' +
+      installHook.toString() +
+      '(window))' +
+      saveNativeValues +
+      detectReact,
+  );
+}
 
 if (typeof exportFunction === 'function') {
   // eslint-disable-next-line no-undef
@@ -106,4 +112,4 @@ if (typeof exportFunction === 'function') {
     window.wrappedJSObject.__REACT_DEVTOOLS_GLOBAL_HOOK__,
     {defineAs: 'clipboardCopyText'},
   );
-}
+}