Fix location information for programs

There appears to be a bug in our use of jison causing the parent location information to be reported to programs. I wasn’t able to work through what might be causing this so instead using the location information of the statements collection to generate the proper location information.

This is a bit of a hack but we are very far behind on the Jison release train and upgrading will likely be a less than pleasant task that doesn’t provide us much benefit.

Fixes #1024

lib/handlebars/compiler/helpers.js

@@ -121,3 +121,28 @@ export function prepareBlock(openBlock, program, inverseAndProgram, close, inver
       openBlock.strip, inverseStrip, close && close.strip,
       this.locInfo(locInfo));
 }
+
+export function prepareProgram(statements, loc) {
+  if (!loc && statements.length) {
+    const first = statements[0].loc,
+          last = statements[statements.length - 1].loc;
+
+    if (first && last) {
+      loc = {
+        source: first.source,
+        start: {
+          line: first.start.line,
+          column: first.start.column
+        },
+        end: {
+          line: last.end.line,
+          column: last.end.column
+        }
+      };
+    }
+  }
+
+  return new this.Program(statements, null, {}, loc);
+}
+
+