dart2js: Use JS_GET_NAME instead of magic constant for catch-all function.

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

Index: pkg/compiler/lib/src/js_emitter/full_emitter/setup_program_builder.dart
diff --git a/pkg/compiler/lib/src/js_emitter/full_emitter/setup_program_builder.dart b/pkg/compiler/lib/src/js_emitter/full_emitter/setup_program_builder.dart
index 4e3cb5fa4bea1c5530c10a957fad94dd62958451..309e12108dc7ac639f617f4b23bd553c023352f9 100644
--- a/pkg/compiler/lib/src/js_emitter/full_emitter/setup_program_builder.dart
+++ b/pkg/compiler/lib/src/js_emitter/full_emitter/setup_program_builder.dart
@@ -747,6 +747,8 @@ function $setupProgramName(programData, typesOffset) {
           mangledNames[name] = reflectionName;
           funcs[0].$reflectionNameField = reflectionName;
           funcs[0].$metadataIndexField = unmangledNameIndex + 1;
+          // The following line installs the [${JsGetName.CALL_CATCH_ALL}]
+          // property for closures.
           if (optionalParameterCount) prototype[unmangledName + "*"] = funcs[0];
         }
       }