Fix a couple of doc comment references - and many spelling mistakes

sdk/lib/core/uri.dart

 // Copyright (c) 2012, 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.
 
 part of dart.core;
 
 // Frequently used character codes.
 const int _SPACE = 0x20;
 const int _PERCENT = 0x25;
 const int _AMPERSAND = 0x26;
@@ skipping 4088 matching lines @@
   setChars(b, "+-.", scheme);
 
   return tables;
 }
 
 // --------------------------------------------------------------------
 // Code that uses the URI scanner table.
 
 /// Scan a string using the [_scannerTables] state machine.
 ///
-/// Scans [uri] from [start] to [end], startig in state [state] and
+/// Scans [uri] from [start] to [end], starting in state [state] and
 /// writing output into [indices].
 ///
 /// Returns the final state.
 int _scan(String uri, int start, int end, int state, List<int> indices) {
   var tables = _scannerTables;
   assert(end <= uri.length);
   for (int i = start; i < end; i++) {
     var table = tables[state];
     // Xor with 0x60 to move range 0x20-0x7f into 0x00-0x5f
     int char = uri.codeUnitAt(i) ^ 0x60;
@@ skipping 510 matching lines @@
   int delta = (text.codeUnitAt(start + 4) ^ _COLON) * 3;
   delta |= text.codeUnitAt(start) ^ 0x64 /*d*/;
   delta |= text.codeUnitAt(start + 1) ^ 0x61 /*a*/;
   delta |= text.codeUnitAt(start + 2) ^ 0x74 /*t*/;
   delta |= text.codeUnitAt(start + 3) ^ 0x61 /*a*/;
   return delta;
 }
 
 /// Helper function returning the length of a string, or `0` for `null`.
 int _stringOrNullLength(String s) => (s == null) ? 0 : s.length;