vm/service/observatory: Add coverage for functions, some tests, and fix buggy filter

runtime/vm/coverage.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/coverage.h"
 
 #include "include/dart_api.h"
 
 #include "vm/compiler.h"
 #include "vm/isolate.h"
@@ skipping 157 matching lines @@
     // We stay within this loop while we are seeing functions from the same
     // source URI.
     while (i < functions.Length()) {
       function ^= functions.At(i);
       script = function.script();
       url = script.url();
       if (!url.Equals(saved_url)) {
         pos_to_line.Clear();
         break;
       }
+      if (!filter->ShouldOutputCoverageFor(lib, saved_url, cls, function)) {
+        i++;
+        continue;
+      }
       CompileAndAdd(function, hits_arr, pos_to_line);
       if (function.HasImplicitClosureFunction()) {
         function = function.ImplicitClosureFunction();
         CompileAndAdd(function, hits_arr, pos_to_line);
       }
       i++;
     }
   }
 
   GrowableObjectArray& closures =
@@ skipping 91 matching lines @@
         cls = it.GetNextClass();
         ASSERT(!cls.IsNull());
         PrintClass(lib, cls, jsarr, filter);
       }
     }
   }
 }
 
 
 }  // namespace dart