Print the first compile-time error in console.

dart/site/try/src/compilation.dart

Index: dart/site/try/src/compilation.dart
diff --git a/dart/site/try/src/compilation.dart b/dart/site/try/src/compilation.dart
index 0fcc7937089ab020dd17cb61b6574183475fd45c..5e2f20594a048afdace4f89245039dbd7435450d 100644
--- a/dart/site/try/src/compilation.dart
+++ b/dart/site/try/src/compilation.dart
@@ -78,6 +78,7 @@ class CompilationProcess {
   bool usesDartHtml = false;
   Worker worker;
   List<String> objectUrls = <String>[];
+  String firstError;
 
   static CompilationProcess current;
 
@@ -139,7 +140,7 @@ class CompilationProcess {
   }
 
   onFail(_) {
-    interaction.onCompilationFailed();
+    interaction.onCompilationFailed(firstError);
   }
 
   onDone(_) {
@@ -240,6 +241,9 @@ self.importScripts("$url");
       interaction.verboseCompilerMessage(message);
       return;
     }
+    if (kind == 'error' && firstError == null) {
+      firstError = message;
+    }
     String uri = diagnostic['uri'];
     if (uri != '${PRIVATE_SCHEME}:/main.dart') {
       interaction.consolePrintLine('$uri: [$kind] $message');