Simplify and fix implicit closure check, speed up Closure_equals

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 90a70005d924b9fce8a3f209072ad3392a980267..12a3f60bd897d16aed00a1ca4014ea31ae0129c9 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -2473,6 +2473,7 @@ class Function : public Object {
       case RawFunction::kInvokeFieldDispatcher:
         return true;
       case RawFunction::kClosureFunction:
+      case RawFunction::kImplicitClosureFunction:
       case RawFunction::kSignatureFunction:
       case RawFunction::kConstructor:
       case RawFunction::kImplicitStaticFinalGetter:
@@ -2497,6 +2498,7 @@ class Function : public Object {
       case RawFunction::kIrregexpFunction:
         return true;
       case RawFunction::kClosureFunction:
+      case RawFunction::kImplicitClosureFunction:
       case RawFunction::kSignatureFunction:
       case RawFunction::kConstructor:
       case RawFunction::kMethodExtractor:
@@ -2773,7 +2775,9 @@ class Function : public Object {
   // Returns true if this function represents a (possibly implicit) closure
   // function.
   bool IsClosureFunction() const {
-    return kind() == RawFunction::kClosureFunction;
+    RawFunction::Kind k = kind();
+    return (k == RawFunction::kClosureFunction) ||
+           (k == RawFunction::kImplicitClosureFunction);
   }
 
   // Returns true if this function represents a generated irregexp function.
@@ -2782,7 +2786,9 @@ class Function : public Object {
   }
 
   // Returns true if this function represents an implicit closure function.
-  bool IsImplicitClosureFunction() const;
+  bool IsImplicitClosureFunction() const {
+    return kind() == RawFunction::kImplicitClosureFunction;
+  }
 
   // Returns true if this function represents a converted closure function.
   bool IsConvertedClosureFunction() const {
@@ -2797,14 +2803,14 @@ class Function : public Object {
   // Returns true if this function represents an implicit static closure
   // function.
   bool IsImplicitStaticClosureFunction() const {
-    return is_static() && IsImplicitClosureFunction();
+    return IsImplicitClosureFunction() && is_static();
   }
   static bool IsImplicitStaticClosureFunction(RawFunction* func);
 
   // Returns true if this function represents an implicit instance closure
   // function.
   bool IsImplicitInstanceClosureFunction() const {
-    return !is_static() && IsImplicitClosureFunction();
+    return IsImplicitClosureFunction() && !is_static();
   }
 
   bool IsConstructorClosureFunction() const;
@@ -2881,6 +2887,11 @@ class Function : public Object {
                                          const Function& parent,
                                          TokenPosition token_pos);
 
+  // Allocates a new Function object representing an implicit closure function.
+  static RawFunction* NewImplicitClosureFunction(const String& name,
+                                                 const Function& parent,
+                                                 TokenPosition token_pos);
+
   // Allocates a new Function object representing a converted closure function.
   static RawFunction* NewConvertedClosureFunction(const String& name,
                                                   const Function& parent,