Sort declarations in edge_origin.dart

Change-Id: I9461d6af29900546cff74879e95f8d729497080b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/180283
Reviewed-by: Samuel Rawlins <srawlins@google.com>
diff --git a/pkg/nnbd_migration/lib/src/edge_origin.dart b/pkg/nnbd_migration/lib/src/edge_origin.dart
index 5b42111..f1d39f6 100644
--- a/pkg/nnbd_migration/lib/src/edge_origin.dart
+++ b/pkg/nnbd_migration/lib/src/edge_origin.dart
@@ -85,6 +85,18 @@
   EdgeOriginKind get kind => EdgeOriginKind.argumentErrorCheckNotNull;
 }
 
+/// An edge origin used for edges that originated because of a tear-off of
+/// `call` on a function type.
+class CallTearOffOrigin extends EdgeOrigin {
+  CallTearOffOrigin(Source source, AstNode node) : super(source, node);
+
+  @override
+  String get description => 'tear-off of .call';
+
+  @override
+  EdgeOriginKind get kind => EdgeOriginKind.callTearOff;
+}
+
 /// Edge origin resulting from the use of a value on the LHS of a compound
 /// assignment.
 class CompoundAssignmentOrigin extends EdgeOrigin {
@@ -397,18 +409,6 @@
   EdgeOriginKind get kind => EdgeOriginKind.listLengthConstructor;
 }
 
-/// An edge origin used for edges that originated because of a tear-off of
-/// `call` on a function type.
-class CallTearOffOrigin extends EdgeOrigin {
-  CallTearOffOrigin(Source source, AstNode node) : super(source, node);
-
-  @override
-  String get description => 'tear-off of .call';
-
-  @override
-  EdgeOriginKind get kind => EdgeOriginKind.callTearOff;
-}
-
 /// An edge origin used for edges that originated because a literal expression
 /// has a known nullability.
 class LiteralOrigin extends EdgeOrigin {