Allow the "img.src='';img.src='.." idiom to clear down images immediately.

Source/core/loader/ImageLoader.cpp

Index: Source/core/loader/ImageLoader.cpp
diff --git a/Source/core/loader/ImageLoader.cpp b/Source/core/loader/ImageLoader.cpp
index 767c9d22abbd153c0576a0d6cd416793cc8e5ff8..d87bcf5712d241df1d4e75084224bbd618ba91cb 100644
--- a/Source/core/loader/ImageLoader.cpp
+++ b/Source/core/loader/ImageLoader.cpp
@@ -356,6 +356,14 @@ void ImageLoader::updateFromElement(UpdateFromElementBehavior updateBehavior)
         doUpdateFromElement(DoNotBypassMainWorldCSP, updateBehavior);
         return;
     }
+    // Allow the idiom "img.src=''; img.src='.." to clear down the image before
+    // an asynchronous load completes.
+    if (imageSourceURL.isEmpty()) {
+        ImageResource* image = m_image.get();
+        if (image)
+            image->removeClient(this);
+        m_image = nullptr;
+    }
     enqueueImageLoadingMicroTask(updateBehavior);
 }