Update comments

Author: vincentfretin

src/systems/material.js

@@ -30,7 +30,7 @@ export var System = registerSystem('material', {
    *
    * @param {string|Element} src - URL or element
    * @param {object} data - Relevant texture properties
-   * @param {function} cb - Callback that receives the texture, or null if loading failed
+   * @param {function} cb - Callback that receives the texture, or null if image loading failed
    */
   loadTexture: function (src, data, cb) {
     this.loadTextureSource(src, function sourceLoaded (source) {
@@ -48,7 +48,7 @@ export var System = registerSystem('material', {
    * Determine whether `src` is an image or video. Then try to load the asset, then call back.
    *
    * @param {string|Element} src - URL or element.
-   * @param {function} cb - Callback that receives the texture source, or null if loading failed.
+   * @param {function} cb - Callback that receives the texture source, or null if image loading failed.
    */
   loadTextureSource: function (src, cb) {
     var self = this;

src/utils/src-loader.js

@@ -142,7 +142,7 @@ function checkIsImage (src, onResult) {
     return;
   }
 
-  // Check file extension first to avoid HEAD request for images.
+  // Check file extension first to avoid HEAD request for common image extensions.
   ext = getExtension(src);
   if (IMAGE_EXTENSIONS.indexOf(ext) !== -1) {
     onResult(true);