Bug 1665215 [wpt PR 25554] - Deny ElementInternals.shadowRoot for pre…

…-created shadow roots, a=testonly

Automatic update from web-platform-tests
Deny ElementInternals.shadowRoot for pre-created shadow roots

Per the spec issue [1], this change disallows the use of
ElementInternals.shadowRoot for shadow roots created prior
to the custom element constructor being run. This protects
potentially-closed shadow roots, created outside of the
custom element, from being revealed to the custom element
itself. (Use case unclear, but this was the request.)

[1] WICG/webcomponents#871

Bug: 1042130
Change-Id: I25192256e8b1334d09ea587f29d64f35d4f5f949
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2412470
Commit-Queue: Kouhei Ueno <kouheichromium.org>
Auto-Submit: Mason Freed <masonfreedchromium.org>
Reviewed-by: Kouhei Ueno <kouheichromium.org>
Cr-Commit-Position: refs/heads/master{#807311}

--

wpt-commits: 8e3392df536283e843589c176ffbc7e00e94e64e
wpt-pr: 25554

UltraBlame original commit: 11691695d1b65041eea7dd2470183b95f4335029

testing/web-platform/tests/shadow-dom/declarative/element-internals-shadowroot.tentative.html

@@ -926,6 +926,200 @@
 '
 )
 ;
+test
+(
+(
+)
+=
+>
+{
+let
+constructed
+=
+false
+;
+const
+element
+=
+document
+.
+createElement
+(
+'
+x
+-
+6
+'
+)
+;
+const
+sr
+=
+element
+.
+attachShadow
+(
+{
+mode
+:
+'
+closed
+'
+}
+)
+;
+assert_true
+(
+sr
+instanceof
+ShadowRoot
+)
+;
+customElements
+.
+define
+(
+'
+x
+-
+6
+'
+class
+extends
+HTMLElement
+{
+constructor
+(
+)
+{
+super
+(
+)
+;
+assert_throws_dom
+(
+'
+NotSupportedError
+'
+(
+)
+=
+>
+this
+.
+attachShadow
+(
+{
+mode
+:
+'
+open
+'
+}
+)
+'
+attachShadow
+already
+called
+'
+)
+;
+const
+elementInternals
+=
+this
+.
+attachInternals
+(
+)
+;
+assert_equals
+(
+elementInternals
+.
+shadowRoot
+null
+'
+ElementInternals
+.
+shadowRoot
+should
+not
+be
+available
+for
+pre
+-
+attached
+shadow
+'
+)
+;
+constructed
+=
+true
+;
+}
+}
+)
+;
+assert_false
+(
+constructed
+)
+;
+customElements
+.
+upgrade
+(
+element
+)
+;
+assert_true
+(
+constructed
+'
+Failed
+to
+construct
+-
+test
+failed
+'
+)
+;
+assert_equals
+(
+element
+.
+shadowRoot
+null
+'
+shadow
+root
+is
+closed
+'
+)
+;
+}
+'
+ElementInternals
+.
+shadowRoot
+doesn
+\
+'
+t
+reveal
+pre
+-
+attached
+closed
+shadowRoot
+'
+)
+;
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