[parser] Manually inline 'isNextIdentifier'

pkg/analyzer/lib/src/dart/ast/ast.dart:

JIT (tokens per microsecond):
2.1064% +/- 1.6771% (0.44 +/- 0.35) (20.97 -> 21.42)

AOT (tokens per microsecond):
No change.

Benchmarker (AOT):
```
msec task-clock:u: -1.2559% +/- 0.6202% (-35.75 +/- 17.65) (2846.58 -> 2810.83)
cycles:u: -1.3051% +/- 0.6113% (-161347113.30 +/- 75579075.11) (12362747585.00 -> 12201400471.70)
instructions:u: -0.6245% +/- 0.0000% (-169931728.50 +/- 1390.09) (27212753414.40 -> 27042821685.90)
seconds time elapsed: -1.2465% +/- 0.6111% (-0.04 +/- 0.02) (2.85 -> 2.81)
seconds user: -1.3083% +/- 0.7709% (-0.04 +/- 0.02) (2.83 -> 2.79)
```


pkg/front_end/lib/src/type_inference/inference_visitor.dart:

JIT (tokens per microsecond):
No change.

AOT (tokens per microsecond):
No change.

Benchmarker (AOT):
```
instructions:u: -0.9284% +/- 0.0000% (-279155451.00 +/- 502.76) (30068900827.90 -> 29789745376.90)
```

Change-Id: I70eaae39d156f77e5e451a8592f6f3dab2da3d67
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/439780
Reviewed-by: Johnni Winther <[email protected]>
Commit-Queue: Jens Johansen <[email protected]>

Author: jensjoha

pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart

@@ -3718,10 +3718,6 @@ class Parser {
     }
   }
 
-  /// Checks whether the next token is (directly) an identifier. If this returns
-  /// true a call to [ensureIdentifier] will return the next token.
-  bool isNextIdentifier(Token token) => token.next?.kind == IDENTIFIER_TOKEN;
-
   /// Parse a simple identifier at the given [token], and return the identifier
   /// that was parsed.
   ///
@@ -8285,8 +8281,10 @@ class Parser {
 
     TypeParamOrArgInfo? potentialTypeArg;
 
-    if (isNextIdentifier(newKeyword)) {
-      Token identifier = newKeyword.next!;
+    Token next = newKeyword.next!;
+
+    if (next.kind == IDENTIFIER_TOKEN) {
+      Token identifier = next;
       String value = identifier.lexeme;
       if ((value == "Map" || value == "Set") &&
           !identifier.next!.isA(TokenType.PERIOD)) {
@@ -8336,7 +8334,7 @@ class Parser {
       // parseConstructorReference.
       // Do special recovery for literal maps/set/list erroneously prepended
       // with 'new'.
-      Token notIdentifier = newKeyword.next!;
+      Token notIdentifier = next;
       String value = notIdentifier.lexeme;
       if (value == "<") {
         potentialTypeArg = computeTypeParamOrArg(newKeyword);
@@ -8739,8 +8737,9 @@ class Parser {
     // send an `handleIdentifier` if we end up recovering.
     TypeParamOrArgInfo? potentialTypeArg;
     Token? afterToken;
-    if (isNextIdentifier(token)) {
-      Token identifier = token.next!;
+    Token next = token.next!;
+    if (next.kind == IDENTIFIER_TOKEN) {
+      Token identifier = next;
       String value = identifier.lexeme;
       if (value == "Map" || value == "Set") {
         potentialTypeArg = computeTypeParamOrArg(identifier);

pkg/front_end/parser_testcases/also-nnbd/issue_39326.dart.intertwined.expect

@@ -57,7 +57,6 @@ parseUnit(main)
                         parsePrimary(;, expression, ConstantPatternContext.none)
                           parseSendOrFunctionLiteral(;, expression, ConstantPatternContext.none)
                             parseSend(;, expression, ConstantPatternContext.none)
-                              isNextIdentifier(;)
                               ensureIdentifier(;, expression)
                                 listener: handleIdentifier(c, expression)
                               listener: handleNoTypeArguments(?.)

pkg/front_end/parser_testcases/also-nnbd/issue_40267_conditional.dart.intertwined.expect

@@ -63,7 +63,6 @@ parseUnit(f)
                       parsePrimary(return, expression, ConstantPatternContext.none)
                         parseSendOrFunctionLiteral(return, expression, ConstantPatternContext.none)
                           parseSend(return, expression, ConstantPatternContext.none)
-                            isNextIdentifier(return)
                             ensureIdentifier(return, expression)
                               listener: handleIdentifier(a, expression)
                             listener: handleNoTypeArguments(?)
@@ -83,7 +82,6 @@ parseUnit(f)
                                         parseSendOrFunctionLiteral([, expression, ConstantPatternContext.none)
                                           looksLikeFunctionBody(])
                                           parseSend([, expression, ConstantPatternContext.none)
-                                            isNextIdentifier([)
                                             ensureIdentifier([, expression)
                                             parseArgumentsOpt(b)
                                               parseArguments(b)
@@ -116,7 +114,6 @@ parseUnit(f)
                                         parseSendOrFunctionLiteral([, expression, ConstantPatternContext.none)
                                           looksLikeFunctionBody(])
                                           parseSend([, expression, ConstantPatternContext.none)
-                                            isNextIdentifier([)
                                             ensureIdentifier([, expression)
                                               listener: handleIdentifier(b, expression)
                                             listener: handleNoTypeArguments(()

pkg/front_end/parser_testcases/also-nnbd/issue_40267_conditional_2.dart.intertwined.expect

@@ -56,7 +56,6 @@ parseUnit(f)
                       parsePrimary(return, expression, ConstantPatternContext.none)
                         parseSendOrFunctionLiteral(return, expression, ConstantPatternContext.none)
                           parseSend(return, expression, ConstantPatternContext.none)
-                            isNextIdentifier(return)
                             ensureIdentifier(return, expression)
                               listener: handleIdentifier(a, expression)
                             listener: handleNoTypeArguments(!=)
@@ -81,7 +80,6 @@ parseUnit(f)
                                         parsePrimary([, expression, ConstantPatternContext.none)
                                           parseSendOrFunctionLiteral([, expression, ConstantPatternContext.none)
                                             parseSend([, expression, ConstantPatternContext.none)
-                                              isNextIdentifier([)
                                               ensureIdentifier([, expression)
                                               parseArgumentsOpt(a)
                         parseExpressionWithoutCascade(:)
@@ -106,7 +104,6 @@ parseUnit(f)
                                       parsePrimary([, expression, ConstantPatternContext.none)
                                         parseSendOrFunctionLiteral([, expression, ConstantPatternContext.none)
                                           parseSend([, expression, ConstantPatternContext.none)
-                                            isNextIdentifier([)
                                             ensureIdentifier([, expression)
                                             parseArgumentsOpt(a)
                       parseExpressionWithoutCascade(:)
@@ -132,7 +129,6 @@ parseUnit(f)
                                       parsePrimary([, expression, ConstantPatternContext.none)
                                         parseSendOrFunctionLiteral([, expression, ConstantPatternContext.none)
                                           parseSend([, expression, ConstantPatternContext.none)
-                                            isNextIdentifier([)
                                             ensureIdentifier([, expression)
                                               listener: handleIdentifier(a, expression)
                                             listener: handleNoTypeArguments(])