Bug 1697525 - Prevent calling printPreview().print() r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D107918
2021-03-12 16:20:24 +00:00 · 2021-03-12 16:20:24 +00:00 · 258f0f6b52
--- a/dom/base/crashtests/1697525.html
+++ b/dom/base/crashtests/1697525.html
@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<script>
+  window.addEventListener('load', () => {
+    SpecialPowers.wrap(self).printPreview()?.print()
+  })
+</script>
--- a/dom/base/crashtests/crashtests.list
+++ b/dom/base/crashtests/crashtests.list
@ -260,3 +260,4 @@ asserts(0-1) load 1623918.html # May hit an assertion if the <input> element's a
 load 1656925.html
 skip-if(Android) load 1665792.html # Print preview on android doesn't fly
 load 1681729.html
+load 1697525.html
--- a/dom/base/nsGlobalWindowOuter.cpp
+++ b/dom/base/nsGlobalWindowOuter.cpp
@ -5241,7 +5241,12 @@ Nullable<WindowProxyHolder> nsGlobalWindowOuter::Print(
  if (docToPrint->IsStaticDocument() &&
      (aIsPreview == IsPreview::Yes ||
       StaticPrefs::print_tab_modal_enabled())) {
-    MOZ_DIAGNOSTIC_ASSERT(aForWindowDotPrint == IsForWindowDotPrint::No);
+    if (aForWindowDotPrint == IsForWindowDotPrint::Yes) {
+      aError.ThrowNotSupportedError(
+          "Calling print() from a print preview is unsupported, did you intend "
+          "to call printPreview() instead?");
+      return nullptr;
+    }
    // We're already a print preview window, just reuse our browsing context /
    // content viewer.
    bc = sourceBC;