Issue 13807. Support for type promotion rules.

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/element/ParameterElementImpl.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/element/ParameterElementImpl.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/element/ParameterElementImpl.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/element/ParameterElementImpl.java
index d8920b7c8746b069916e4ae5a78663e1b4006ff8..8e069df4f4a06488d986e42a956bda1c8c9e383c 100644
--- a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/element/ParameterElementImpl.java
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/element/ParameterElementImpl.java
@@ -27,6 +27,11 @@ import com.google.dart.engine.utilities.source.SourceRange;
  */
 public class ParameterElementImpl extends VariableElementImpl implements ParameterElement {
   /**
+   * Is {@code true} if this variable is potentially mutated somewhere in its scope.
+   */
+  private boolean isPotentiallyMutated;
+
+  /**
    * An array containing all of the parameters defined by this parameter element. There will only be
    * parameters if this parameter is a function typed parameter.
    */
@@ -125,6 +130,18 @@ public class ParameterElementImpl extends VariableElementImpl implements Paramet
     return false;
   }
 
+  @Override
+  public boolean isPotentiallyMutated() {
+    return isPotentiallyMutated;
+  }
+
+  /**
+   * Specifies that this variable is potentially mutated somewhere in its scope.
+   */
+  public void markPotentiallyMutated() {
+    isPotentiallyMutated = true;
+  }
+
   /**
    * Set the range of the default value for this parameter to the range starting at the given offset
    * with the given length.