#145421 Fix glyph padding in STB atlas impl. (#51585)

See the associated issue for description and screenshots.

Fixes issue #145421 [as described here.](https://github.com/flutter/flutter/issues/145421)

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style
diff --git a/impeller/typographer/backends/stb/typographer_context_stb.cc b/impeller/typographer/backends/stb/typographer_context_stb.cc
index 6c5bcad..ffcda77 100644
--- a/impeller/typographer/backends/stb/typographer_context_stb.cc
+++ b/impeller/typographer/backends/stb/typographer_context_stb.cc
@@ -220,8 +220,7 @@
   // Glyph in place
   if (!has_color || DISABLE_COLOR_FONT_SUPPORT) {
     stbtt_MakeGlyphBitmap(typeface_stb->GetFontInfo(), output,
-                          location.GetWidth() - kPadding,
-                          location.GetHeight() - kPadding,
+                          location.GetWidth(), location.GetHeight(),
                           bitmap->GetRowBytes(), scale_x, scale_y, glyph.index);
   } else {
     // But for color bitmaps we need to get the glyph pixels and then carry all