[FIX] base: fix sourcemap header offset

in b1d57adf6ff3 the size of the header added to source files while
concatenating them was reduced, but the corresponding offset use when
generating source maps was not adapted, causing source maps to drift
further and further from the actual source location the further in the
compiled asset the line is.

This commit fixes that by decrementing the header offset as needed.

closes odoo/odoo#102651

X-original-commit: 4d4585ee6c905c2a3adc4692098c1a3544417629
Signed-off-by: Géry Debongnie <ged@odoo.com>
Signed-off-by: Samuel Degueldre <sad@odoo.com>

odoo/addons/base/models/assetsbundle.py

@@ -429,7 +429,7 @@ class AssetsBundle(object):
         )
         content_bundle_list = []
         content_line_count = 0
-        line_header = 6  # number of lines added by with_header()
+        line_header = 5  # number of lines added by with_header()
         for asset in self.javascripts:
             if asset.is_transpiled:
                 # '+ 3' corresponds to the 3 lines added at the beginning of the file during transpilation.