New rule: oversized images (#276)

New rule: oversized images

lib/metadata/policies.js

@@ -914,6 +914,15 @@ var policies = {
         "hasOffenders": true,
         "unit": 'bytes'
     },
+    "imagesTooLarge": {
+        "tool": "redownload",
+        "label": "Oversized images",
+        "message": "<p>This is the number of images with a width >800px on mobile or >1500px on desktop. Try </p><p>Please ignore if the file is used as a sprite.</p><p>Please note that Yellow Lab Tools' engine (PhantomJS) is not compatible with image srcset (unless you use a polyfill). This can lead to incorrect detection.</p>",
+        "isOkThreshold": 0,
+        "isBadThreshold": 5,
+        "isAbnormalThreshold": 10,
+        "hasOffenders": true
+    },
     "gzipCompression": {
         "tool": "redownload",
         "label": "Gzip compression",

lib/metadata/scoreProfileGeneric.json

@@ -5,6 +5,7 @@
             "policies": {
                 "totalWeight": 5,
                 "imageOptimization": 2,
+                "imagesTooLarge": 2,
                 "gzipCompression": 2,
                 "fileMinification": 1
             }