Refactor SharedFunctionInfo::IsBuiltin.

src/compiler/js-inlining-heuristic.cc

Index: src/compiler/js-inlining-heuristic.cc
diff --git a/src/compiler/js-inlining-heuristic.cc b/src/compiler/js-inlining-heuristic.cc
index d6229c2d6467d4b26776ca2d018e792934af87c7..672d322a249adcdd0be110502b6d8516aa911837 100644
--- a/src/compiler/js-inlining-heuristic.cc
+++ b/src/compiler/js-inlining-heuristic.cc
@@ -46,8 +46,8 @@ bool CanInlineFunction(Handle<JSFunction> function) {
   // Built-in functions are handled by the JSBuiltinReducer.
   if (function->shared()->HasBuiltinFunctionId()) return false;
 
-  // Don't inline builtins.
-  if (function->shared()->IsBuiltin()) return false;
+  // Only choose user code for inlining.
+  if (!function->shared()->IsUserJavaScript()) return false;
 
   // Quick check on the size of the AST to avoid parsing large candidate.
   if (function->shared()->ast_node_count() > FLAG_max_inlined_nodes) {