dart2js-kernel: map rasta 'read' node in 'field ??= e'

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

Index: pkg/compiler/lib/src/kernel/kernel_visitor.dart
diff --git a/pkg/compiler/lib/src/kernel/kernel_visitor.dart b/pkg/compiler/lib/src/kernel/kernel_visitor.dart
index 905ea0f5477c365910614ec6b1903358e6698aca..b2ba6de949dc671cb35a39a142064674490ba709 100644
--- a/pkg/compiler/lib/src/kernel/kernel_visitor.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_visitor.dart
@@ -1318,8 +1318,17 @@ class KernelVisitor extends Object
     Accessor accessor = (receiver == null)
         ? new ThisPropertyAccessor(irName, null, null)
         : PropertyAccessor.make(visitForValue(receiver), irName, null, null);
-    return accessor.buildNullAwareAssignment(visitForValue(rhs), null,
+    return _finishSetIfNull(node, accessor, rhs);
+  }
+
+  ir.Expression _finishSetIfNull(Send node, Accessor accessor, Node rhs) {
+    ir.Expression result = accessor.buildNullAwareAssignment(
+        visitForValue(rhs), null,
         voidContext: isVoidContext);
+    if (accessor.builtGetter != null) {
+      kernel.nodeToAst[accessor.builtGetter] = node;
+    }
+    return result;
   }
 
   @override
@@ -1551,9 +1560,8 @@ class KernelVisitor extends Object
   @override
   ir.Expression visitIfNotNullDynamicPropertySetIfNull(
       Send node, Node receiver, Name name, Node rhs, _) {
-    return buildNullAwarePropertyAccessor(receiver, name)
-        .buildNullAwareAssignment(visitForValue(rhs), null,
-            voidContext: isVoidContext);
+    return _finishSetIfNull(
+        node, buildNullAwarePropertyAccessor(receiver, name), rhs);
   }
 
   ir.LogicalExpression buildLogicalExpression(
@@ -1892,9 +1900,7 @@ class KernelVisitor extends Object
   ir.Expression handleLocalSetIfNulls(
       SendSet node, LocalElement local, Node rhs, _,
       {bool isSetterValid}) {
-    return new VariableAccessor(getLocal(local)).buildNullAwareAssignment(
-        visitForValue(rhs), null,
-        voidContext: isVoidContext);
+    return _finishSetIfNull(node, new VariableAccessor(getLocal(local)), rhs);
   }
 
   @override
@@ -2009,9 +2015,7 @@ class KernelVisitor extends Object
     if (setterKind == CompoundSetter.INVALID) {
       setter = null;
     }
-    return buildStaticAccessor(getter, setter).buildNullAwareAssignment(
-        visitForValue(rhs), null,
-        voidContext: isVoidContext);
+    return _finishSetIfNull(node, buildStaticAccessor(getter, setter), rhs);
   }
 
   ir.VariableDeclaration getLocal(LocalElement local) {
@@ -2456,9 +2460,8 @@ class KernelVisitor extends Object
     if (setterKind == CompoundSetter.INVALID) {
       setter = null;
     }
-    return buildSuperPropertyAccessor(getter, setter).buildNullAwareAssignment(
-        visitForValue(rhs), null,
-        voidContext: isVoidContext);
+    return _finishSetIfNull(
+        node, buildSuperPropertyAccessor(getter, setter), rhs);
   }
 
   @override
@@ -2685,9 +2688,8 @@ class KernelVisitor extends Object
   @override
   ir.Expression visitTypeVariableTypeLiteralSetIfNull(
       Send node, TypeVariableElement element, Node rhs, _) {
-    return new ReadOnlyAccessor(buildTypeVariable(element))
-        .buildNullAwareAssignment(visitForValue(rhs), null,
-            voidContext: isVoidContext);
+    return _finishSetIfNull(
+        node, new ReadOnlyAccessor(buildTypeVariable(element)), rhs);
   }
 
   @override
@@ -2751,17 +2753,14 @@ class KernelVisitor extends Object
   @override
   ir.Expression visitIndexSetIfNull(
       SendSet node, Node receiver, Node index, Node rhs, _) {
-    return buildIndexAccessor(receiver, index).buildNullAwareAssignment(
-        visitForValue(rhs), null,
-        voidContext: isVoidContext);
+    return _finishSetIfNull(node, buildIndexAccessor(receiver, index), rhs);
   }
 
   @override
   ir.Expression visitSuperIndexSetIfNull(SendSet node, MethodElement getter,
       MethodElement setter, Node index, Node rhs, _) {
-    return buildSuperIndexAccessor(index, getter, setter)
-        .buildNullAwareAssignment(visitForValue(rhs), null,
-            voidContext: isVoidContext);
+    return _finishSetIfNull(
+        node, buildSuperIndexAccessor(index, getter, setter), rhs);
   }
 
   @override