Add if_clause

so we can visit the first line of the `block_if_statement` in a single
node.

Author: inaki-amatria

grammar.js

@@ -1338,17 +1338,21 @@ module.exports = grammar({
     )),
 
     block_if_statement: $ => seq(
+      $.if_clause,
+      repeat($._statement),
+      repeat($.elseif_clause),
+      optional($.else_clause),
+      optional($.statement_label),
+      $.end_if_statement
+    ),
+
+    if_clause: $ => seq(
       optional($.block_label_start_expression),
       caseInsensitive('if'),
       $._parenthesized_expression,
       caseInsensitive('then'),
       optional($._block_label),
       $.end_of_statement,
-      repeat($._statement),
-      repeat($.elseif_clause),
-      optional($.else_clause),
-      optional($.statement_label),
-      $.end_if_statement
     ),
 
     end_if_statement: $ => seq(

src/grammar.json

@@ -14661,6 +14661,57 @@
       }
     },
     "block_if_statement": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "SYMBOL",
+          "name": "if_clause"
+        },
+        {
+          "type": "REPEAT",
+          "content": {
+            "type": "SYMBOL",
+            "name": "_statement"
+          }
+        },
+        {
+          "type": "REPEAT",
+          "content": {
+            "type": "SYMBOL",
+            "name": "elseif_clause"
+          }
+        },
+        {
+          "type": "CHOICE",
+          "members": [
+            {
+              "type": "SYMBOL",
+              "name": "else_clause"
+            },
+            {
+              "type": "BLANK"
+            }
+          ]
+        },
+        {
+          "type": "CHOICE",
+          "members": [
+            {
+              "type": "SYMBOL",
+              "name": "statement_label"
+            },
+            {
+              "type": "BLANK"
+            }
+          ]
+        },
+        {
+          "type": "SYMBOL",
+          "name": "end_if_statement"
+        }
+      ]
+    },
+    "if_clause": {
       "type": "SEQ",
       "members": [
         {
@@ -14712,48 +14763,6 @@
         {
           "type": "SYMBOL",
           "name": "end_of_statement"
-        },
-        {
-          "type": "REPEAT",
-          "content": {
-            "type": "SYMBOL",
-            "name": "_statement"
-          }
-        },
-        {
-          "type": "REPEAT",
-          "content": {
-            "type": "SYMBOL",
-            "name": "elseif_clause"
-          }
-        },
-        {
-          "type": "CHOICE",
-          "members": [
-            {
-              "type": "SYMBOL",
-              "name": "else_clause"
-            },
-            {
-              "type": "BLANK"
-            }
-          ]
-        },
-        {
-          "type": "CHOICE",
-          "members": [
-            {
-              "type": "SYMBOL",
-              "name": "statement_label"
-            },
-            {
-              "type": "BLANK"
-            }
-          ]
-        },
-        {
-          "type": "SYMBOL",
-          "name": "end_if_statement"
         }
       ]
     },