Disable image lazy loading when scripting is disabled

This CL disables image lazy loading for images in frames in which
scripting is disabled. The HTML Standard mandates that image lazy
loading be disabled in these cases, as a privacy-protection measure.
See [1].

[1]: https://html.spec.whatwg.org/multipage/images.html#will-lazy-load-image-steps

R=kinuko@chromium.org, sclittle@chromium.org

Bug: 1005881
Change-Id: Ib675b46ee1d9bb10119172893547cb80b0308ab1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2127415
Commit-Queue: Dominic Farolino <dom@chromium.org>
Reviewed-by: Scott Little <sclittle@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#754960}

third_party/blink/renderer/core/loader/lazy_image_helper.cc

@@ -6,6 +6,7 @@
 
 #include "third_party/blink/renderer/core/dom/document.h"
 #include "third_party/blink/renderer/core/dom/element.h"
+#include "third_party/blink/renderer/core/execution_context/execution_context.h"
 #include "third_party/blink/renderer/core/frame/frame_owner.h"
 #include "third_party/blink/renderer/core/frame/local_frame.h"
 #include "third_party/blink/renderer/core/frame/web_feature.h"
@@ -110,6 +111,11 @@ LazyImageHelper::DetermineEligibilityAndTrackVisibilityMetrics(
   if (!url.ProtocolIsInHTTPFamily())
     return LazyImageHelper::Eligibility::kDisabled;
 
+  // Do not lazyload image elements when JavaScript is disabled, regardless of
+  // the `loading` attribute.
+  if (!frame.GetDocument()->CanExecuteScripts(kNotAboutToExecuteScript))
+    return LazyImageHelper::Eligibility::kDisabled;
+
   const auto lazy_load_image_setting = frame.GetLazyLoadImageSetting();
   LoadingAttrValue loading_attr = GetLoadingAttrValue(*html_image);
   bool is_fully_loadable =

third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/the-img-element/image-loading-lazy-in-script-disabled-iframe-expected.txt

-This is a testharness.js-based test.
-FAIL Images with loading='lazy' in script disabled iframe are not handled
-       as 'lazy' assert_true: lazy-load image shouldn't be honored in script disabled iframe expected true got false
-Harness: the test ran to completion.
-