dart2js: add function coverage tracking in dart2js output, dumpinfo, and

pkg/compiler/lib/src/js_backend/backend.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 js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
@@ skipping 1433 matching lines @@
         }
       } else {
         // If the constant-handler was not able to produce a result we have to
         // go through the builder (below) to generate the lazy initializer for
         // the static variable.
         // We also need to register the use of the cyclic-error helper.
         compiler.enqueuer.codegen.registerStaticUse(getCyclicThrowHelper());
       }
     }
 
-    generatedCode[element] = functionCompiler.compile(work);
+    jsAst.Fun code = functionCompiler.compile(work);
+    if (const bool.fromEnvironment('instrumentForCoverage')
+        && compiler.dumpInfo) {
+      // TODO(sigmund): do this properly (e.g. add an embedded global, etc).
+      code.body.statements.insert(0, js.statement(
+          '__record_use("${element.hashCode}", "${element.name}")'));
+    }
+
+    generatedCode[element] = code;
     return const WorldImpact();
   }
 
   native.NativeEnqueuer nativeResolutionEnqueuer(Enqueuer world) {
     return new native.NativeResolutionEnqueuer(world, compiler);
   }
 
   native.NativeEnqueuer nativeCodegenEnqueuer(Enqueuer world) {
     return new native.NativeCodegenEnqueuer(world, compiler, emitter);
   }
@@ skipping 1604 matching lines @@
   }
 }
 
 /// Records that [constant] is used by the element behind [registry].
 class Dependency {
   final ConstantValue constant;
   final Element annotatedElement;
 
   const Dependency(this.constant, this.annotatedElement);
 }