Handle final var lambda variables

The start position of `final` variable is apparently after the token for
`final`, this works around that by inlining a call to `visitVariable` and
dropping the `sync` call that asserts the start position of the current
node matches the next token.

Fixes #959

PiperOrigin-RevId: 564710136

Author: cushon

core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java

@@ -1250,7 +1250,10 @@ public Void visitLambdaExpression(LambdaExpressionTree node, Void unused) {
         token(",");
         builder.breakOp(" ");
       }
-      scan(parameter, null);
+      visitVariables(
+          ImmutableList.of(parameter),
+          DeclarationKind.NONE,
+          fieldAnnotationDirection(parameter.getModifiers()));
       first = false;
     }
     if (parens) {

core/src/test/resources/com/google/googlejavaformat/java/testdata/I959.input

@@ -0,0 +1,5 @@
+class I959 {
+  public void test() {
+      new File(".").listFiles((final var dir, final var name) -> true);
+  }
+}

core/src/test/resources/com/google/googlejavaformat/java/testdata/I959.output

@@ -0,0 +1,5 @@
+class I959 {
+  public void test() {
+    new File(".").listFiles((final var dir, final var name) -> true);
+  }
+}