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

pkg/compiler/lib/src/dump_info.dart

Index: pkg/compiler/lib/src/dump_info.dart
diff --git a/pkg/compiler/lib/src/dump_info.dart b/pkg/compiler/lib/src/dump_info.dart
index 898337ba3a1143f0631d38135839300e75ad1227..5ea735862a3e3211362e0c403351fd27d5d412eb 100644
--- a/pkg/compiler/lib/src/dump_info.dart
+++ b/pkg/compiler/lib/src/dump_info.dart
@@ -128,6 +128,9 @@ class ElementInfoCollector extends BaseElementVisitor<Info, dynamic> {
 
     FieldInfo info = new FieldInfo(
         name: element.name,
+        // We use element.hashCode because it is globally unique and it is
+        // available while we are doing codegen.
+        coverageId: '${element.hashCode}',
         type: '${element.type}',
         inferredType: '$inferredType',
         size: size,
@@ -268,6 +271,9 @@ class ElementInfoCollector extends BaseElementVisitor<Info, dynamic> {
 
     FunctionInfo info = new FunctionInfo(
         name: name,
+        // We use element.hashCode because it is globally unique and it is
+        // available while we are doing codegen.
+        coverageId: '${element.hashCode}',
         modifiers: modifiers,
         size: size,
         returnType: returnType,