[es7] Implement async functions parsing

src/globals.h

Index: src/globals.h
diff --git a/src/globals.h b/src/globals.h
index 0e30a9468890cbca262bb992a4e5fddf2bba0fa2..7bdb8a4f1e065bd347ff96e5c657dd633bbbc23f 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -925,14 +925,15 @@ enum Signedness { kSigned, kUnsigned };
 enum FunctionKind {
   kNormalFunction = 0,
   kArrowFunction = 1 << 0,
-  kGeneratorFunction = 1 << 1,
-  kConciseMethod = 1 << 2,
+  kAsyncFunction = 1 << 1,
+  kGeneratorFunction = 1 << 2,
+  kConciseMethod = 1 << 3,
   kConciseGeneratorMethod = kGeneratorFunction | kConciseMethod,
-  kAccessorFunction = 1 << 3,
-  kDefaultConstructor = 1 << 4,
-  kSubclassConstructor = 1 << 5,
-  kBaseConstructor = 1 << 6,
-  kInObjectLiteral = 1 << 7,
+  kAccessorFunction = 1 << 4,
+  kDefaultConstructor = 1 << 5,
+  kSubclassConstructor = 1 << 6,
+  kBaseConstructor = 1 << 7,
+  kInObjectLiteral = 1 << 8,
   kDefaultBaseConstructor = kDefaultConstructor | kBaseConstructor,
   kDefaultSubclassConstructor = kDefaultConstructor | kSubclassConstructor,
   kConciseMethodInObjectLiteral = kConciseMethod | kInObjectLiteral,
@@ -945,6 +946,7 @@ enum FunctionKind {
 inline bool IsValidFunctionKind(FunctionKind kind) {
   return kind == FunctionKind::kNormalFunction ||
          kind == FunctionKind::kArrowFunction ||
+         kind == FunctionKind::kAsyncFunction ||
          kind == FunctionKind::kGeneratorFunction ||
          kind == FunctionKind::kConciseMethod ||
          kind == FunctionKind::kConciseGeneratorMethod ||
@@ -965,6 +967,12 @@ inline bool IsArrowFunction(FunctionKind kind) {
 }
 
 
+inline bool IsAsyncFunction(FunctionKind kind) {
+  DCHECK(IsValidFunctionKind(kind));
+  return kind & FunctionKind::kAsyncFunction;
+}
+
+
 inline bool IsGeneratorFunction(FunctionKind kind) {
   DCHECK(IsValidFunctionKind(kind));
   return kind & FunctionKind::kGeneratorFunction;