Fix 56 hints in pkg/compiler

pkg/compiler/lib/src/compiler.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 dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 891 matching lines @@
     _currentElement = element;
     try {
       return f();
     } on SpannableAssertionFailure catch (ex) {
       if (!hasCrashed) {
         reportAssertionFailure(ex);
         pleaseReportCrash();
       }
       hasCrashed = true;
       rethrow;
-    } on StackOverflowError catch (ex) {
+    } on StackOverflowError {
       // We cannot report anything useful in this case, because we
       // do not have enough stack space.
       rethrow;
     } catch (ex) {
       if (hasCrashed) rethrow;
       try {
         unhandledExceptionOnElement(element);
       } catch (doubleFault) {
         // Ignoring exceptions in exception handling.
       }
@@ skipping 833 matching lines @@
     }
     for (Element e in new Set.from(resolved)) {
       if (e.isClass ||
           e.isField ||
           e.isTypeVariable ||
           e.isTypedef ||
           identical(e.kind, ElementKind.ABSTRACT_FIELD)) {
         resolved.remove(e);
       }
       if (identical(e.kind, ElementKind.GENERATIVE_CONSTRUCTOR)) {
-        ClassElement enclosingClass = e.enclosingClass;
         resolved.remove(e);
-
       }
       if (backend.isBackendLibrary(e.library)) {
         resolved.remove(e);
       }
     }
     log('Excess resolution work: ${resolved.length}.');
     for (Element e in resolved) {
       reportWarning(e,
           MessageKind.GENERIC,
           {'text': 'Warning: $e resolved but not compiled.'});
@@ skipping 115 matching lines @@
         node, messageKind.message(arguments, terseDiagnostics), kind);
   }
 
   void reportDiagnostic(Spannable span,
                         Message message,
                         api.Diagnostic kind);
 
   void reportAssertionFailure(SpannableAssertionFailure ex) {
     String message = (ex.message != null) ? tryToString(ex.message)
                                           : tryToString(ex);
-    SourceSpan span = spanFromSpannable(ex.node);
     reportDiagnosticInternal(
         ex.node, MessageKind.GENERIC, {'text': message}, api.Diagnostic.CRASH);
   }
 
   SourceSpan spanFromTokens(Token begin, Token end, [Uri uri]) {
     if (begin == null || end == null) {
       // TODO(ahe): We can almost always do better. Often it is only
       // end that is null. Otherwise, we probably know the current
       // URI.
       throw 'Cannot find tokens to produce error message.';
@@ skipping 542 matching lines @@
     return futureClass.computeType(compiler).createInstantiation([elementType]);
   }
 
   @override
   InterfaceType streamType([DartType elementType = const DynamicType()]) {
     return streamClass.computeType(compiler).createInstantiation([elementType]);
   }
 }
 
 typedef void InternalErrorFunction(Spannable location, String message);