Migrate UnlinkedVariable.constExpr to UnlinkedExecutable.bodyExpr.

pkg/analyzer/lib/src/summary/summarize_elements.dart

Index: pkg/analyzer/lib/src/summary/summarize_elements.dart
diff --git a/pkg/analyzer/lib/src/summary/summarize_elements.dart b/pkg/analyzer/lib/src/summary/summarize_elements.dart
index cd2adec178c64e37e25c5e8c3ef204e965d31eee..432d414429e37d6438a6d5b4c028092784acfbeb 100644
--- a/pkg/analyzer/lib/src/summary/summarize_elements.dart
+++ b/pkg/analyzer/lib/src/summary/summarize_elements.dart
@@ -1133,11 +1133,15 @@ class _CompilationUnitSerializer {
     b.isConst = variable.isConst;
     b.documentationComment = serializeDocumentation(variable);
     b.annotations = serializeAnnotations(variable);
+    // TODO(scheglov) VariableMember.initializer is not implemented
+    if (variable is! VariableMember && variable.initializer != null) {
+      b.initializer = serializeExecutable(variable.initializer);
+    }
     if (variable is ConstVariableElement) {
       ConstVariableElement constVariable = variable as ConstVariableElement;
       Expression initializer = constVariable.constantInitializer;
       if (initializer != null) {
-        b.constExpr =
+        b.initializer?.bodyExpr =
             serializeConstExpr(variable, variable.initializer, initializer);
       }
     }
@@ -1162,10 +1166,6 @@ class _CompilationUnitSerializer {
         b.visibleLength = visibleRange.length;
       }
     }
-    // TODO(scheglov) VariableMember.initializer is not implemented
-    if (variable is! VariableMember && variable.initializer != null) {
-      b.initializer = serializeExecutable(variable.initializer);
-    }
     return b;
   }