Move source maps package to the dart repo, so it can be used by other internal

pkg/source_maps/test/printer_test.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library test.printer_test;
+
+import 'dart:json' as json;
+import 'package:unittest/unittest.dart';
+import 'package:source_maps/printer.dart';
+import 'package:source_maps/span.dart';
+import 'common.dart';
+
+main() {
+  test('printer', () {
+    var printer = new Printer('output.dart');
+    printer..add('var ')
+           ..mark(inputVar1)
+           ..add('x = 3;\n')
+           ..mark(inputFunction)
+           ..add('f(')
+           ..mark(inputVar2)
+           ..add('y) => ')
+           ..mark(inputExpr)
+           ..add('x + y;\n');
+    expect(printer.text, OUTPUT);
+    expect(printer.map, json.stringify(EXPECTED_MAP));
+  });
+
+  test('printer projecting marks', () {
+    var out = INPUT.replaceAll('long', '_s');
+    var printer = new Printer('output2.dart');
+
+    var segments = INPUT.split('long');
+    expect(segments.length, 6);
+    printer..mark(ispan(0, 0))
+        ..add(segments[0], projectMarks: true)
+        ..mark(inputVar1)
+        ..add('_s')
+        ..add(segments[1], projectMarks: true)
+        ..mark(inputFunction)
+        ..add('_s')
+        ..add(segments[2], projectMarks: true)
+        ..mark(inputVar2)
+        ..add('_s')
+        ..add(segments[3], projectMarks: true)
+        ..mark(inputExpr)
+        ..add('_s')
+        ..add(segments[4], projectMarks: true)
+        ..add('_s')
+        ..add(segments[5], projectMarks: true);
+
+    expect(printer.text, out);
+    // 8 new lines in the source map:
+    expect(printer.map.split(';').length, 8);
+
+    asFixed(Span s) => new FixedSpan(s.sourceUrl,
+        s.start.offset, s.start.line, s.start.column,
+        text: s.text, isIdentifier: s.isIdentifier);
+
+    // The result is the same if we use fixed positions
+    var printer2 = new Printer('output2.dart');
+    printer2..mark(new FixedSpan('input.dart', 0, 0, 0))
+        ..add(segments[0], projectMarks: true)
+        ..mark(asFixed(inputVar1))
+        ..add('_s')
+        ..add(segments[1], projectMarks: true)
+        ..mark(asFixed(inputFunction))
+        ..add('_s')
+        ..add(segments[2], projectMarks: true)
+        ..mark(asFixed(inputVar2))
+        ..add('_s')
+        ..add(segments[3], projectMarks: true)
+        ..mark(asFixed(inputExpr))
+        ..add('_s')
+        ..add(segments[4], projectMarks: true)
+        ..add('_s')
+        ..add(segments[5], projectMarks: true);
+
+    expect(printer2.text, out);
+    expect(printer2.map, printer.map);
+  });
+}