Add an internal flag to the dart2js compiler to enable/diable inlining

lib/compiler/implementation/compiler.dart

Index: lib/compiler/implementation/compiler.dart
diff --git a/lib/compiler/implementation/compiler.dart b/lib/compiler/implementation/compiler.dart
index 40d7b97c40c0c68ea1385cd7c99d8766951e3198..00bf51e9ece8f15ef50b3a0063b5fc0bc0f1b4ae 100644
--- a/lib/compiler/implementation/compiler.dart
+++ b/lib/compiler/implementation/compiler.dart
@@ -95,6 +95,8 @@ class Compiler implements DiagnosticListener {
   final bool enableTypeAssertions;
   final bool enableUserAssertions;
 
+  bool disableInlining = false;
+
   // TODO(5074): Remove this field once we don't accept the
   // deprecated parameter specification.
   static final bool REJECT_NAMED_ARGUMENT_AS_POSITIONAL = false;