Merge branch '5.2' into 5.3

* 5.2:
  Fix incompatible implicit float-to-int conversions
  [Translation] Don't pass null to strtoupper()
  cs fix
  [String] Fix implicit float-to-int casts
  [DependencyInjection] Don't pass null to trim()
  Add return types to JsonSerializable implementations
  Fix Serializable deprecations triggered by token mocks
  Add missing security translations

Author: derrabus

AbstractUnicodeString.php

@@ -480,22 +480,22 @@ private function pad(int $len, self $pad, int $type): parent
 
         switch ($type) {
             case \STR_PAD_RIGHT:
-                return $this->append(str_repeat($pad->string, $freeLen / $padLen).($len ? $pad->slice(0, $len) : ''));
+                return $this->append(str_repeat($pad->string, intdiv($freeLen, $padLen)).($len ? $pad->slice(0, $len) : ''));
 
             case \STR_PAD_LEFT:
-                return $this->prepend(str_repeat($pad->string, $freeLen / $padLen).($len ? $pad->slice(0, $len) : ''));
+                return $this->prepend(str_repeat($pad->string, intdiv($freeLen, $padLen)).($len ? $pad->slice(0, $len) : ''));
 
             case \STR_PAD_BOTH:
                 $freeLen /= 2;
 
                 $rightLen = ceil($freeLen);
                 $len = $rightLen % $padLen;
-                $str = $this->append(str_repeat($pad->string, $rightLen / $padLen).($len ? $pad->slice(0, $len) : ''));
+                $str = $this->append(str_repeat($pad->string, intdiv($rightLen, $padLen)).($len ? $pad->slice(0, $len) : ''));
 
                 $leftLen = floor($freeLen);
                 $len = $leftLen % $padLen;
 
-                return $str->prepend(str_repeat($pad->string, $leftLen / $padLen).($len ? $pad->slice(0, $len) : ''));
+                return $str->prepend(str_repeat($pad->string, intdiv($leftLen, $padLen)).($len ? $pad->slice(0, $len) : ''));
 
             default:
                 throw new InvalidArgumentException('Invalid padding type.');