Only support the new source_span spans in barback.

This releases barback 0.15.0, code_transformers 0.2.0+1, observe 0.11.0+2,
polymer 0.12.0+3, and smoke 0.2.0+3.

BUG=19930
R=blois@google.com, rnystrom@google.com, sigmund@google.com

Review URL: https://codereview.chromium.org//430973002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@38762 260f80e4-7a28-3924-810f-c04153c831b5

lib/src/barback.dart

@@ -38,7 +38,7 @@ import 'version.dart';
 ///
 /// [compat]: https://gist.github.com/nex3/10942218
 final pubConstraints = {
-  "barback": new VersionConstraint.parse(">=0.13.0 <0.14.3"),
+  "barback": new VersionConstraint.parse(">=0.13.0 <0.15.1"),
   "source_span": new VersionConstraint.parse(">=1.0.0 <2.0.0"),
   "stack_trace": new VersionConstraint.parse(">=0.9.1 <2.0.0")
 };

lib/src/barback/asset_environment.dart

@@ -673,7 +673,7 @@ void _log(LogEntry entry) {
   var prefix = "[${prefixParts.join(' ')}]:";
   var message = entry.message;
   if (entry.span != null) {
-    message = entry.span.getLocationMessage(entry.message);
+    message = entry.span.message(entry.message);
   }
 
   switch (entry.level) {

lib/src/log.dart

@@ -10,7 +10,6 @@ import 'dart:convert';
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
-import 'package:source_maps/source_maps.dart';
 import 'package:source_span/source_span.dart';
 import 'package:stack_trace/stack_trace.dart';
 
@@ -316,9 +315,7 @@ void exception(exception, [StackTrace trace]) {
 
   // This is basically the top-level exception handler so that we don't
   // spew a stack trace on our users.
-  if (exception is SpanException) {
-    error(exception.toString(useColors: canUseSpecialChars));
-  } else if (exception is SourceSpanException) {
+  if (exception is SourceSpanException) {
     error(exception.toString(color: canUseSpecialChars));
   } else {
     error(getErrorMessage(exception));
@@ -510,8 +507,7 @@ class _JsonLogger {
     }
 
     // If the error came from a file, include the path.
-    if ((error is SpanException || error is SourceSpanException) &&
-        error.span.sourceUrl != null) {
+    if (error is SourceSpanException && error.span.sourceUrl != null) {
       errorJson["path"] = p.fromUri(error.span.sourceUrl);
     }