Use the ol.DEBUG_WEBGL flag to debug shader sources

src/ol/index.js

@@ -83,6 +83,14 @@ ol.ENABLE_RASTER_REPROJECTION = true;
 ol.ENABLE_WEBGL = true;
 
 
+/**
+ * @define {boolean} Include debuggable shader sources.  Default is `true`.
+ *     This should be set to `false` for production builds (if `ol.ENABLE_WEBGL`
+ *     is `true`).
+ */
+ol.DEBUG_WEBGL = true;
+
+
 /**
  * @define {number} The size in pixels of the first atlas image. Default is
  * `256`.