fix PHP7 build

Author: staabm

tests/PHPStan/Analyser/nsrt/array-combine-php7.php

@@ -33,15 +33,15 @@ function withBoolKey(): void
 	$c = [false, 'red', 'yellow'];
 	$d = ['avocado', 'apple', 'banana'];
 
-	assertType("array{: 'avocado', red: 'apple', yellow: 'banana'}", array_combine($c, $d));
+	assertType("array{'': 'avocado', red: 'apple', yellow: 'banana'}", array_combine($c, $d));
 }
 
 function withFloatKey(): void
 {
 	$a = [1.5, 'red', 'yellow'];
 	$b = ['avocado', 'apple', 'banana'];
 
-	assertType("array{1.5: 'avocado', red: 'apple', yellow: 'banana'}", array_combine($a, $b));
+	assertType("array{'1.5': 'avocado', red: 'apple', yellow: 'banana'}", array_combine($a, $b));
 }
 
 function withIntegerKey(): void