Lexical "this" capture

Author: ef4

packages/@glimmer/syntax/lib/v2/builders.ts

@@ -208,7 +208,6 @@ export class Builder {
     isTemplateLocal: boolean,
     loc: SourceSpan
   ): ASTv2.VariableReference {
-    assert(name !== 'this', `You called builders.var() with 'this'. Call builders.this instead`);
     assert(
       name[0] !== '@',
       `You called builders.var() with '${name}'. Call builders.at('${name}') instead`

packages/@glimmer/syntax/lib/v2/normalize.ts

@@ -323,6 +323,10 @@ class ExpressionNormalizer {
 
     switch (head.type) {
       case 'ThisHead':
+        if (block.hasBinding('this')) {
+          let [symbol, isRoot] = table.get('this');
+          return block.builder.localVar('this', symbol, isRoot, offsets);
+        }
         return builder.self(offsets);
       case 'AtHead': {
         let symbol = table.allocateNamed(head.name);