Add FunctionEntity.asyncMarker and refactor SourceInformationStrategy to avoid ResolvedAst

pkg/compiler/lib/src/kernel/elements.dart

Index: pkg/compiler/lib/src/kernel/elements.dart
diff --git a/pkg/compiler/lib/src/kernel/elements.dart b/pkg/compiler/lib/src/kernel/elements.dart
index 305c41a10f1dc1655c7112e4135fc450f39aafc1..2996a03f0d583abd715a3183d85d413b944fa157 100644
--- a/pkg/compiler/lib/src/kernel/elements.dart
+++ b/pkg/compiler/lib/src/kernel/elements.dart
@@ -92,9 +92,10 @@ abstract class KMember implements MemberEntity {
 abstract class KFunction extends KMember implements FunctionEntity {
   final ParameterStructure parameterStructure;
   final bool isExternal;
+  final AsyncMarker asyncMarker;
 
   KFunction(int memberIndex, KLibrary library, KClass enclosingClass, Name name,
-      this.parameterStructure,
+      this.parameterStructure, this.asyncMarker,
       {bool isStatic: false, this.isExternal: false})
       : super(memberIndex, library, enclosingClass, name, isStatic: isStatic);
 }
@@ -105,7 +106,7 @@ abstract class KConstructor extends KFunction implements ConstructorEntity {
   KConstructor(int memberIndex, KClass enclosingClass, Name name,
       ParameterStructure parameterStructure, {bool isExternal, this.isConst})
       : super(memberIndex, enclosingClass.library, enclosingClass, name,
-            parameterStructure,
+            parameterStructure, AsyncMarker.SYNC,
             isExternal: isExternal);
 
   @override
@@ -153,9 +154,10 @@ class KMethod extends KFunction {
   final bool isAbstract;
 
   KMethod(int memberIndex, KLibrary library, KClass enclosingClass, Name name,
-      ParameterStructure parameterStructure,
+      ParameterStructure parameterStructure, AsyncMarker asyncMarker,
       {bool isStatic, bool isExternal, this.isAbstract})
       : super(memberIndex, library, enclosingClass, name, parameterStructure,
+            asyncMarker,
             isStatic: isStatic, isExternal: isExternal);
 
   @override
@@ -168,9 +170,10 @@ class KGetter extends KFunction {
   final bool isAbstract;
 
   KGetter(int memberIndex, KLibrary library, KClass enclosingClass, Name name,
+      AsyncMarker asyncMarker,
       {bool isStatic, bool isExternal, this.isAbstract})
       : super(memberIndex, library, enclosingClass, name,
-            const ParameterStructure.getter(),
+            const ParameterStructure.getter(), asyncMarker,
             isStatic: isStatic, isExternal: isExternal);
 
   @override
@@ -185,7 +188,7 @@ class KSetter extends KFunction {
   KSetter(int memberIndex, KLibrary library, KClass enclosingClass, Name name,
       {bool isStatic, bool isExternal, this.isAbstract})
       : super(memberIndex, library, enclosingClass, name,
-            const ParameterStructure.setter(),
+            const ParameterStructure.setter(), AsyncMarker.SYNC,
             isStatic: isStatic, isExternal: isExternal);
 
   @override