break adds a breakpoint, clear removes it.
Formats:
break - break at current position
break 13 - break at line 13, current script
break 13:20 - break at line 13, col 20, current script
break script.dart:13 - break at line 13, script.dart
break script.dart:13:20 - break at line 13, col 20, script.dart
break main - break at function
break FormatException - break at constructor
break _SHA1._updateHash - break at method
clear supports the same location specifiers.
TAB completion works for all of these formats.
The protocol does not yet support setting column-specific or
function/constructor/method breakpoints. For now we just support
parsing these formats.
Review URL: https://codereview.chromium.org//918003002
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@43733 260f80e4-7a28-3924-810f-c04153c831b5