Add CompilationUnitElement.lineInfo and resynthesize it.

pkg/analyzer/test/src/summary/resynthesize_common.dart

Index: pkg/analyzer/test/src/summary/resynthesize_common.dart
diff --git a/pkg/analyzer/test/src/summary/resynthesize_common.dart b/pkg/analyzer/test/src/summary/resynthesize_common.dart
index fd40ab40929f0eae8292ecd11d69c0ae84c1bf1e..c7eec5d188e64f320a2346bd2efbd59d1853adc2 100644
--- a/pkg/analyzer/test/src/summary/resynthesize_common.dart
+++ b/pkg/analyzer/test/src/summary/resynthesize_common.dart
@@ -260,6 +260,7 @@ abstract class AbstractResynthesizeTest extends AbstractSingleUnitTest {
     compareUriReferencedElements(resynthesized, original, desc);
     expect(resynthesized.source, original.source);
     expect(resynthesized.librarySource, original.librarySource);
+    compareLineInfo(resynthesized.lineInfo, original.lineInfo);
     expect(resynthesized.types.length, original.types.length,
         reason: '$desc types');
     for (int i = 0; i < resynthesized.types.length; i++) {
@@ -821,6 +822,11 @@ abstract class AbstractResynthesizeTest extends AbstractSingleUnitTest {
     compareElements(resynthesized, original, desc);
   }
 
+  void compareLineInfo(LineInfo resynthesized, LineInfo original) {
+    expect(resynthesized.lineCount, original.lineCount);
+    expect(resynthesized.lineStarts, original.lineStarts);
+  }
+
   void compareLocalElementsOfExecutable(ExecutableElement resynthesized,
       ExecutableElement original, String desc) {
     if (original is! Member) {