Remove old workaround for partial-token-parsing

src/verus.pest

@@ -841,19 +841,16 @@ expr_inner_no_struct = _{
   | path_expr   // Needs to be last, or it matches against keywords like "while"  
 }
 
-// The next three rules are defined to be atomic, since they
-// all require one or more explicit whitespace tokens.
-// This avoids, e.g., parsing "assert" has "as sert".
-expr_as = ${
-    as_str ~ WHITESPACE+ ~ type
+expr_as = {
+    as_str ~ type
 }
 
-expr_has = ${
-    has_str ~ WHITESPACE+ ~ expr
+expr_has = {
+    has_str ~ expr
 }
 
-expr_is = ${
-    is_str ~ WHITESPACE+ ~ type
+expr_is = {
+    is_str ~ type
 }
 
 expr_outer = _{
@@ -1153,8 +1150,8 @@ underscore_expr = {
     attr* ~ "_"
 }
 
-box_expr = ${
-    attr* ~ box_str ~ WHITESPACE+ ~ expr
+box_expr = {
+    attr* ~ box_str ~ expr
 }
 
 //*************************//