[1.0] Fixes 1317 Google Analytics plugin; updates attachHistory listener logic

.editorconfig

@@ -0,0 +1,19 @@
+# editorconfig.org
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[{*.json, *.svg}]
+indent_style = space
+indent_size = 4
+
+# Matches the exact package.json, or *rc
+[{package.json,*.yml,*rc}]
+indent_style = space
+indent_size = 2

packages/gatsby-plugin-google-analytics/src/gatsby-browser.js

@@ -1,7 +1,7 @@
-exports.onRouteUpdate = function(location) {
+exports.onRouteUpdate = function({ location }) {
   // Don't track while developing.
   if (process.env.NODE_ENV === `production`) {
-    ga(`set`, `page`, location.pathname)
+    ga(`set`, `page`, (location || {}).pathname)
     ga(`send`, `pageview`)
   }
 }

packages/gatsby/src/cache-dir/production-app.js

@@ -77,11 +77,13 @@ window.___navigateTo = navigateTo
 const history = createHistory()
 
 function attachToHistory(history) {
-  window.___history = history
+  if(!window.___history) {
+    window.___history = history
 
-  history.listen((location, action) => {
-    apiRunner(`onRouteUpdate`, { location, action })
-  })
+    history.listen((location, action) => {
+      apiRunner(`onRouteUpdate`, { location, action })
+    })
+  }
 }
 
 function shouldUpdateScroll(prevRouterProps, { location: { pathname } }) {