use CYPRESS_FORCE_BROWSER_SCALE to force standard resolution

Author: flotwig

packages/server/lib/browsers/chrome.coffee

@@ -159,6 +159,19 @@ _connectToChromeRemoteInterface = (port) ->
     debug("received wsUrl %s for port %d", wsUrl, port)
 
     CriClient.create(wsUrl)
+  .then (client) ->
+    if process.env.CYPRESS_FORCE_BROWSER_SCALE
+      client.send('Emulation.setDeviceMetricsOverride', {
+        width: 1280,
+        height: 720,
+        deviceScaleFactor: 1,
+        mobile: false,
+        screenWidth: 1280,
+        screenHeight: 720,
+      }).then ->
+        client
+
+    client
 
 _maybeRecordVideo = (options) ->
   return (client) ->

packages/server/lib/cypress.coffee

@@ -56,7 +56,7 @@ module.exports = {
         ## then display a warning to the user
         if not options.invokedFromCli
           warning("INVOKED_BINARY_OUTSIDE_NPM_MODULE")
-        
+
         ## just run the gui code directly here
         ## and pass our options directly to main
         debug("running Electron currently")
@@ -131,7 +131,7 @@ module.exports = {
 
     options = require("./util/args").toObject(argv)
 
-    if options.runProject and not options.headed
+    if (options.runProject and not options.headed) or process.env.CYPRESS_FORCE_BROWSER_SCALE
       # scale the electron browser window
       # to force retina screens to not
       # upsample their images when offscreen

packages/server/test/support/helpers/e2e.coffee

@@ -210,6 +210,8 @@ module.exports = {
       ## can take a long time (5-15 secs)
       @timeout(human("2 minutes"))
 
+      process.env.CYPRESS_FORCE_BROWSER_SCALE = '1'
+
       Fixtures.scaffold()
 
       sinon.stub(process, "exit")