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

pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart

Index: pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart b/pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart
index 254a0f7cfe078cad4187e72c3701bf321475cbac..deec2b902efbf7fc6586c1f036a9e1e466f25557 100644
--- a/pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/full_emitter/emitter.dart
@@ -1438,6 +1438,21 @@ class Emitter implements js_emitter.Emitter {
             };
        }
 
+       if (#hasInstrumentation) {
+         var __record_buffer = []; // TODO(sigmund): define as a proper global.
+         function __record_use(id, name) {
+           if (__record_buffer.length == 0) {
+             window.setTimeout(function () {
+               var xhr = new XMLHttpRequest();
+               xhr.open("POST", "/coverage_uri_to_amend_by_server");
+               xhr.send(JSON.stringify(__record_buffer));
+               __record_buffer = [];
+             }, 1000);
+           }
+           __record_buffer.push([id, name]);
+         }
+       }
+
        if (#isProgramSplit) {
          /// We collect all the global state, so it can be passed to the
          /// initializer of deferred files.
@@ -1530,6 +1545,9 @@ class Emitter implements js_emitter.Emitter {
     """, {
       "disableVariableRenaming": js.comment("/* ::norenaming:: */"),
       "hasIncrementalSupport": compiler.hasIncrementalSupport,
+      // TODO(sigmund): add flag
+      "hasInstrumentation": const bool.fromEnvironment('instrumentForCoverage')
+          && compiler.dumpInfo,
       "helper": js('this.#', [namer.incrementalHelperName]),
       "schemaChange": buildSchemaChangeFunction(),
       "addMethod": buildIncrementalAddMethod(),