Issue 12566. Add 'Who declares' and 'Who uses' items into omnibox.

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/index/IndexContributor.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/index/IndexContributor.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/index/IndexContributor.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/index/IndexContributor.java
index bd35a5261fc03605c5addd77a32687396d8ac8a3..1ed9b3b79176f29e4669f3e7607bb20710cc2159 100644
--- a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/index/IndexContributor.java
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/index/IndexContributor.java
@@ -29,6 +29,7 @@ import com.google.dart.engine.ast.ConstructorName;
 import com.google.dart.engine.ast.ExportDirective;
 import com.google.dart.engine.ast.Expression;
 import com.google.dart.engine.ast.ExtendsClause;
+import com.google.dart.engine.ast.FormalParameter;
 import com.google.dart.engine.ast.FunctionDeclaration;
 import com.google.dart.engine.ast.FunctionTypeAlias;
 import com.google.dart.engine.ast.Identifier;
@@ -437,6 +438,17 @@ public class IndexContributor extends GeneralizingASTVisitor<Void> {
   }
 
   @Override
+  public Void visitFormalParameter(FormalParameter node) {
+    ParameterElement element = node.getElement();
+    enterScope(element);
+    try {
+      return super.visitFormalParameter(node);
+    } finally {
+      exitScope();
+    }
+  }
+
+  @Override
   public Void visitFunctionDeclaration(FunctionDeclaration node) {
     Element element = node.getElement();
     recordElementDefinition(element, IndexConstants.DEFINES_FUNCTION);