Add minimal yaml support to the engine

pkg/analyzer/lib/src/generated/source.dart

Index: pkg/analyzer/lib/src/generated/source.dart
diff --git a/pkg/analyzer/lib/src/generated/source.dart b/pkg/analyzer/lib/src/generated/source.dart
index 0fae83a01853d234957ecf8969010ff3314a0e34..a3662f98300382935fef0fb52266cf72806c1db8 100644
--- a/pkg/analyzer/lib/src/generated/source.dart
+++ b/pkg/analyzer/lib/src/generated/source.dart
@@ -200,6 +200,13 @@ class LineInfo {
   factory LineInfo(List<int> _lineStarts) => new LineInfoWithCount(_lineStarts);
 
   /**
+   * Initialize a newly created set of line information corresponding to the
+   * given file [content].
+   */
+  factory LineInfo.fromContent(String content) =>
+      new LineInfoWithCount(StringUtilities.computeLineStarts(content));
+
+  /**
    * Initialize a newly created set of line information to represent the data
    * encoded in the given list of [_lineStarts].
    */