Fixed invalid read in CONST_STRING dereference, reported by Nikic

Author: laruence

Zend/zend_language_parser.y

@@ -802,7 +802,7 @@ expr_without_variable:
 combined_scalar_offset:
 	  combined_scalar '[' dim_offset ']' { zend_do_begin_variable_parse(TSRMLS_C); fetch_array_dim(&$$, &$1, &$3 TSRMLS_CC); }
 	| combined_scalar_offset '[' dim_offset ']' { fetch_array_dim(&$$, &$1, &$3 TSRMLS_CC); }
-    | T_CONSTANT_ENCAPSED_STRING '[' dim_offset ']' { zend_do_begin_variable_parse(TSRMLS_C); fetch_array_dim(&$$, &$1, &$3 TSRMLS_CC); }
+    | T_CONSTANT_ENCAPSED_STRING '[' dim_offset ']' { $1.EA = 0; zend_do_begin_variable_parse(TSRMLS_C); fetch_array_dim(&$$, &$1, &$3 TSRMLS_CC); }
 
 combined_scalar:
       T_ARRAY '(' array_pair_list ')' { $$ = $3; }