Check emitter constants and fix tearOffName for JConstructorBody

pkg/compiler/lib/src/js_emitter/model.dart

Index: pkg/compiler/lib/src/js_emitter/model.dart
diff --git a/pkg/compiler/lib/src/js_emitter/model.dart b/pkg/compiler/lib/src/js_emitter/model.dart
index 364e2c57e015d1e66715754ffa124c9a6f3f5aba..9692ef13bd5fe606c3f7ce096c030208b7ef834f 100644
--- a/pkg/compiler/lib/src/js_emitter/model.dart
+++ b/pkg/compiler/lib/src/js_emitter/model.dart
@@ -392,6 +392,11 @@ abstract class Method {
   final js.Expression code;
 
   Method(this.element, this.name, this.code);
+
+  String toString() {
+    return 'method[name=${name},element=${element}'

[sra1, 2017/07/11 18:24:05]

FWIW I prefer these debug-oriented strings to have the same name as the class
and use parens and source-code-like spacing, e.g.

    Method(name=x, element=z)

rather than

    method[name=x,element=z].

If we consistently use the class name then it is easier to know where to look
for the definition.

[Johnni Winther, 2017/07/12 10:03:24]

Will change in a follow-up CL.

+        ',code=${js.nodeToString(code)}]';
+  }
 }
 
 /// A method that corresponds to a method in the original Dart program.