Bug 1415761 - Catch the exception and rethrow it after invoking custo…

…m elements reactions; r=bz

The spec was unclear on how CEReactions interact with thrown exceptions; see whatwg/html#3217.
The spec is now being clarified in whatwg/html#3235.

MozReview-Commit-ID: 521HprTRS7k

UltraBlame original commit: df3695afb47e0598e3fb1425a7e2a0d16adf35ee

dom/base/CustomElementRegistry.h

@@ -2661,18 +2661,65 @@ final
 {
 public
 :
-explicit
+/
+/
+JSContext
+is
+allowed
+to
+be
+a
+nullptr
+if
+we
+are
+guaranteeing
+that
+we
+'
+re
+/
+/
+not
+doing
+something
+that
+might
+throw
+but
+not
+finish
+reporting
+a
+JS
+/
+/
+exception
+during
+the
+lifetime
+of
+the
+AutoCEReaction
+.
 AutoCEReaction
 (
 CustomElementReactionsStack
 *
 aReactionsStack
+JSContext
+*
+aCx
 )
 :
 mReactionsStack
 (
 aReactionsStack
 )
+mCx
+(
+aCx
+)
 {
 mReactionsStack
 -
@@ -2687,6 +2734,28 @@ AutoCEReaction
 (
 )
 {
+Maybe
+<
+JS
+:
+:
+AutoSaveExceptionState
+>
+ases
+;
+if
+(
+mCx
+)
+{
+ases
+.
+emplace
+(
+mCx
+)
+;
+}
 mReactionsStack
 -
 >
@@ -2703,6 +2772,10 @@ CustomElementReactionsStack
 >
 mReactionsStack
 ;
+JSContext
+*
+mCx
+;
 }
 ;
 }

dom/base/nsDocument.cpp

@@ -36933,6 +36933,7 @@ GetDocGroup
 CustomElementReactionsStack
 (
 )
+aCx
 )
 ;
 /

dom/bindings/Codegen.py

@@ -61473,6 +61473,7 @@
 emplace
 (
 reactionsStack
+cx
 )
 ;
 

parser/html/nsHtml5TreeOperation.cpp

@@ -2509,6 +2509,7 @@ GetDocGroup
 CustomElementReactionsStack
 (
 )
+nullptr
 )
 ;
 nsCOMPtr

testing/web-platform/meta/MANIFEST.json

@@ -1955791,6 +1955791,40 @@ custom
 -
 elements
 /
+reactions
+/
+with
+-
+exceptions
+.
+html
+"
+:
+[
+[
+"
+/
+custom
+-
+elements
+/
+reactions
+/
+with
+-
+exceptions
+.
+html
+"
+{
+}
+]
+]
+"
+custom
+-
+elements
+/
 upgrading
 .
 html
@@ -3628005,6 +3628039,28 @@ custom
 -
 elements
 /
+reactions
+/
+with
+-
+exceptions
+.
+html
+"
+:
+[
+"
+b72ee82a3d98c61683e62c4834f54269898e12d5
+"
+"
+testharness
+"
+]
+"
+custom
+-
+elements
+/
 resources
 /
 custom