Issue 6201. Clean up to replace 'interface' with 'abstract class'

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/refactoring/code/ExtractUtils.java

Index: editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/refactoring/code/ExtractUtils.java
diff --git a/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/refactoring/code/ExtractUtils.java b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/refactoring/code/ExtractUtils.java
index ca86da17b7a21f59ecc3487b365b7303d3f22b1d..913148cb7a1fdc50a3fef3eff7bd5b2c53756e5b 100644
--- a/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/refactoring/code/ExtractUtils.java
+++ b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/refactoring/code/ExtractUtils.java
@@ -474,6 +474,23 @@ public class ExtractUtils {
   }
 
   /**
+   * @return the index of the first non-whitespace character after given index.
+   */
+  public int getNonWhitespaceForward(int index) {
+    int length = buffer.getLength();
+    // skip whitespace characters
+    while (index < length) {
+      char c = buffer.getChar(index);
+      if (!Character.isWhitespace(c)) {
+        break;
+      }
+      index++;
+    }
+    // done
+    return index;
+  }
+
+  /**
    * @return the line prefix consisting of spaces and tabs on the left from the given offset.
    */
   public String getPrefix(int endIndex) {