Better error when force-compile fails

pkg/dev_compiler/lib/src/compiler/compiler.dart

Index: pkg/dev_compiler/lib/src/compiler/compiler.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/compiler.dart b/pkg/dev_compiler/lib/src/compiler/compiler.dart
index 2df03f45418ccd3ef57ae741c35abb36310cd1c4..25050935e44561463f251bedc8edc80cae7d4e24 100644
--- a/pkg/dev_compiler/lib/src/compiler/compiler.dart
+++ b/pkg/dev_compiler/lib/src/compiler/compiler.dart
@@ -215,9 +215,20 @@ class ModuleCompiler {
         errors.any((e) => _isFatalError(e, options))) {
       return new JSModuleFile.invalid(unit.name, messages, options);
     }
-    var codeGenerator =
-        new CodeGenerator(context, summaryData, options, _extensionTypes);
-    return codeGenerator.compile(unit, trees, messages);
+
+    try {
+      var codeGenerator =
+          new CodeGenerator(context, summaryData, options, _extensionTypes);
+      return codeGenerator.compile(unit, trees, messages);
+    } catch (e) {
+      if (errors.any((e) => _isFatalError(e, options))) {
+        // Force compilation failed.  Suppress the exception and report
+        // the static errors instead.
+        assert(options.unsafeForceCompile);
+        return new JSModuleFile.invalid(unit.name, messages, options);
+      }
+      rethrow;
+    }
   }
 }