Insert implicit downcasts in kernel strong mode.

pkg/kernel/lib/ast.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// -----------------------------------------------------------------------
 ///                           ERROR HANDLING
 /// -----------------------------------------------------------------------
 ///
 /// As a rule of thumb, errors that can be detected statically are handled by
 /// the frontend, typically by translating the erroneous code into a 'throw' or
@@ skipping 926 matching lines @@
   }
 
   DartType get setterType {
     return isSetter
         ? function.positionalParameters[0].type
         : const BottomType();
   }
 
   _MemberAccessor get _getterInterface => _reference;
   _MemberAccessor get _setterInterface => _reference;
+
+  Location _getLocationInEnclosingFile(int offset) {
+    return enclosingProgram.getLocation(fileUri, offset);
+  }
 }
 
 enum ProcedureKind {
   Method,
   Getter,
   Setter,
   Operator,
   Factory,
 }
 
@@ skipping 2583 matching lines @@
       int pivot = lines[mid];
       if (pivot <= offset) {
         low = mid;
       } else {
         high = mid - 1;
       }
     }
     int lineIndex = low;
     int lineStart = lines[lineIndex];
     int lineNumber = 1 + lineIndex;
-    int columnNumber = offset - lineStart;
+    int columnNumber = 1 + offset - lineStart;
     return new Location(file, lineNumber, columnNumber);
   }
 }
 
 /// A tuple with file, line, and column number, for displaying human-readable
 /// locations.
 class Location {
   final String file;
   final int line; // 1-based.
   final int column; // 1-based.
@@ skipping 90 matching lines @@
     }
   }
 }
 
 class Source {
   final List<int> lineStarts;
   final String source;
 
   Source(this.lineStarts, this.source);
 }