New NodeLocator which uses positions of characters, not between them.

pkg/analyzer/test/generated/ast_test.dart

Index: pkg/analyzer/test/generated/ast_test.dart
diff --git a/pkg/analyzer/test/generated/ast_test.dart b/pkg/analyzer/test/generated/ast_test.dart
index 24958de3a3a80bcfb3dc1d2f797e2393fa32e4f3..fd888ccec26c3eb1346c6aa1a73fa612d5f3fc65 100644
--- a/pkg/analyzer/test/generated/ast_test.dart
+++ b/pkg/analyzer/test/generated/ast_test.dart
@@ -29,6 +29,7 @@ main() {
   runReflectiveTests(IndexExpressionTest);
   runReflectiveTests(NodeListTest);
   runReflectiveTests(NodeLocatorTest);
+  runReflectiveTests(NodeLocator2Test);
   runReflectiveTests(SimpleIdentifierTest);
   runReflectiveTests(SimpleStringLiteralTest);
   runReflectiveTests(StringInterpolationTest);
@@ -945,6 +946,35 @@ class NodeListTest extends EngineTestCase {
 }
 
 @reflectiveTest
+class NodeLocator2Test extends ParserTestCase {
+  void test_onlyStartOffset() {
+    CompilationUnit unit = ParserTestCase.parseCompilationUnit(' int vv;');
+    TopLevelVariableDeclaration declaration = unit.declarations[0];
+    VariableDeclarationList variableList = declaration.variables;
+    Identifier typeName = variableList.type.name;
+    expect(new NodeLocator2(0).searchWithin(unit), same(unit));
+    expect(new NodeLocator2(1).searchWithin(unit), same(typeName));
+    expect(new NodeLocator2(2).searchWithin(unit), same(typeName));
+    expect(new NodeLocator2(3).searchWithin(unit), same(typeName));
+    expect(new NodeLocator2(4).searchWithin(unit), same(variableList));
+  }
+
+  void test_startEndOffset() {
+    CompilationUnit unit = ParserTestCase.parseCompilationUnit(' int vv; ');
+    TopLevelVariableDeclaration declaration = unit.declarations[0];
+    VariableDeclarationList variableList = declaration.variables;
+    Identifier typeName = variableList.type.name;
+    SimpleIdentifier varName = variableList.variables[0].name;
+    expect(new NodeLocator2(0, 2).searchWithin(unit), same(unit));
+    expect(new NodeLocator2(1, 2).searchWithin(unit), same(typeName));
+    expect(new NodeLocator2(1, 3).searchWithin(unit), same(typeName));
+    expect(new NodeLocator2(1, 4).searchWithin(unit), same(variableList));
+    expect(new NodeLocator2(5, 6).searchWithin(unit), same(varName));
+    expect(new NodeLocator2(5, 7).searchWithin(unit), same(declaration));
+  }
+}
+
+@reflectiveTest
 class NodeLocatorTest extends ParserTestCase {
   void test_range() {
     CompilationUnit unit =