Revert "feat: use the i flag for Regex"

Since upstream tree-sitter hasn't been released yet (nor the node
 package updated), it is cumbersome to build things.  For now keep
 the old regexp.
This reverts commit 99d845cd94.

grammar.js

@@ -3,9 +3,13 @@
  */
 const reservedWord = word =>
    // word ||  // when debugging conflict error msgs
-   alias(reserved(word), word)
+   alias(reserved(caseInsensitive(word)), word)
    ;
-const reserved = regex => token(prec(2, new RegExp(regex, 'i')));
+const reserved = regex => token(prec(2, new RegExp(regex)));
+const caseInsensitive = word =>
+  word.split('')
+    .map(letter => `[${letter}${letter.toUpperCase()}]`)
+    .join('');
 
 /**
  * A list of rules

src/tree_sitter/parser.h

@@ -13,8 +13,9 @@ extern "C" {
 #define ts_builtin_sym_end 0
 #define TREE_SITTER_SERIALIZATION_BUFFER_SIZE 1024
 
-#ifndef TREE_SITTER_API_H_
 typedef uint16_t TSStateId;
+
+#ifndef TREE_SITTER_API_H_
 typedef uint16_t TSSymbol;
 typedef uint16_t TSFieldId;
 typedef struct TSLanguage TSLanguage;
@@ -139,8 +140,7 @@ struct TSLanguage {
   lexer->advance(lexer, skip);  \
   start:                        \
   skip = false;                 \
-  lookahead = lexer->lookahead; \
-  eof = lexer->eof(lexer);
+  lookahead = lexer->lookahead;
 
 #define ADVANCE(state_value) \
   {                          \
@@ -166,7 +166,7 @@ struct TSLanguage {
  *  Parse Table Macros
  */
 
-#define SMALL_STATE(id) ((id) - LARGE_STATE_COUNT)
+#define SMALL_STATE(id) id - LARGE_STATE_COUNT
 
 #define STATE(id) id
 
@@ -176,7 +176,7 @@ struct TSLanguage {
   {{                                  \
     .shift = {                        \
       .type = TSParseActionTypeShift, \
-      .state = (state_value)          \
+      .state = state_value            \
     }                                 \
   }}
 
@@ -184,7 +184,7 @@ struct TSLanguage {
   {{                                  \
     .shift = {                        \
       .type = TSParseActionTypeShift, \
-      .state = (state_value),         \
+      .state = state_value,           \
       .repetition = true              \
     }                                 \
   }}