Bug 353575 - Allow IDTracker to look up elements in <svg:use> shadow …

…trees. r=smaug

Other UAs allow this, and it seems in the general consensus of
WICG/webcomponents#179.

This matches WebKit's behavior. Blink, for some reason shows red on the
test-case, probably because they're not doing quite this, but they
manage to render masks inside the display: none symbol element or such.

Differential Revision: https://phabricator.services.mozilla.com/D72610

UltraBlame original commit: 8efff752175e177108adceddb73a60f98f8cdd27

dom/base/IDTracker.cpp

@@ -133,6 +133,24 @@ h
 #
 include
 "
+mozilla
+/
+dom
+/
+DocumentOrShadowRoot
+.
+h
+"
+#
+include
+"
+nsAtom
+.
+h
+"
+#
+include
+"
 nsContentUtils
 .
 h
@@ -165,20 +183,72 @@ nsCycleCollectionParticipant
 .
 h
 "
+#
+include
+"
+nsStringFwd
+.
+h
+"
 namespace
 mozilla
 {
 namespace
 dom
 {
 static
+Element
+*
+LookupElement
+(
+DocumentOrShadowRoot
+&
+aDocOrShadow
+const
+nsAString
+&
+aRef
+bool
+aReferenceImage
+)
+{
+if
+(
+aReferenceImage
+)
+{
+return
+aDocOrShadow
+.
+LookupImageElement
+(
+aRef
+)
+;
+}
+return
+aDocOrShadow
+.
+GetElementById
+(
+aRef
+)
+;
+}
+static
 DocumentOrShadowRoot
 *
-DocOrShadowFromContent
+FindTreeToWatch
 (
 nsIContent
 &
 aContent
+const
+nsAString
+&
+aID
+bool
+aReferenceImage
 )
 {
 ShadowRoot
@@ -194,16 +264,17 @@ GetContainingShadow
 /
 /
 We
-never
-look
-in
+allow
+looking
+outside
+an
 <
 svg
 :
 use
 >
 shadow
-trees
+tree
 for
 backwards
 compat
@@ -230,6 +301,58 @@ use
 )
 )
 {
+/
+/
+<
+svg
+:
+use
+>
+shadow
+trees
+are
+immutable
+so
+we
+can
+just
+early
+-
+out
+if
+we
+find
+/
+/
+our
+relevant
+element
+instead
+of
+having
+to
+support
+watching
+multiple
+/
+/
+trees
+.
+if
+(
+LookupElement
+(
+*
+shadow
+aID
+aReferenceImage
+)
+)
+{
+return
+shadow
+;
+}
 shadow
 =
 shadow
@@ -371,16 +494,6 @@ OwnerDoc
 (
 )
 ;
-DocumentOrShadowRoot
-*
-docOrShadow
-=
-DocOrShadowFromContent
-(
-*
-aFromContent
-)
-;
 auto
 encoding
 =
@@ -553,6 +666,10 @@ GetDocumentURI
 isEqualExceptRef
 )
 ;
+DocumentOrShadowRoot
+*
+docOrShadow
+;
 if
 (
 NS_FAILED
@@ -658,6 +775,19 @@ a
 bit
 }
 }
+else
+{
+docOrShadow
+=
+FindTreeToWatch
+(
+*
+aFromContent
+ref
+aReferenceImage
+)
+;
+}
 if
 (
 aWatch
@@ -718,23 +848,34 @@ mReferencingImage
 =
 false
 ;
+nsDependentAtomString
+str
+(
+aID
+)
+;
 DocumentOrShadowRoot
 *
 docOrShadow
 =
-DocOrShadowFromContent
+FindTreeToWatch
 (
 aFrom
+str
+/
+*
+aReferenceImage
+=
+*
+/
+false
 )
 ;
 HaveNewDocumentOrShadowRoot
 (
 docOrShadow
 aWatch
-nsDependentAtomString
-(
-aID
-)
+str
 )
 ;
 }
@@ -805,31 +946,19 @@ aDocOrShadow
 return
 ;
 }
+if
+(
 Element
 *
 e
 =
-mReferencingImage
-?
-aDocOrShadow
--
->
-LookupImageElement
+LookupElement
 (
-aRef
-)
-:
+*
 aDocOrShadow
--
->
-GetElementById
-(
 aRef
+mReferencingImage
 )
-;
-if
-(
-e
 )
 {
 mElement
@@ -1131,7 +1260,8 @@ aData
 {
 NS_ASSERTION
 (
-PL_strcmp
+!
+strcmp
 (
 aTopic
 "
@@ -1144,9 +1274,6 @@ document
 created
 "
 )
-=
-=
-0
 "
 Unexpected
 topic

layout/reftests/svg/fragid-shadow-7.html

@@ -155,7 +155,7 @@
 fill
 =
 "
-lime
+red
 "
 width
 =
@@ -204,7 +204,7 @@
 fill
 =
 "
-red
+lime
 "
 width
 =

layout/reftests/svg/fragid-shadow-8.html

@@ -42,7 +42,7 @@
 fill
 =
 "
-lime
+red
 "
 width
 =
@@ -91,7 +91,7 @@
 fill
 =
 "
-red
+lime
 "
 width
 =