gistfile1.diff

diff --git a/src/components/servo-gfx/font_context.rs b/src/components/servo-gfx/font_context.rs
index 87c1b63..880c7d3 100644
--- a/src/components/servo-gfx/font_context.rs
+++ b/src/components/servo-gfx/font_context.rs
@@ -38,6 +38,7 @@ pub trait FontContextHandleMethods {
 pub struct FontContext {
     instance_cache: MonoCache<FontDescriptor, @mut Font>,
     shaper_cache: MonoCache<FontDescriptor, @Shaper>,
+    group_cache: MonoCache<SpecifiedFontStyle, @FontGroup>,
     font_list: Option<FontList>, // only needed by layout
     handle: FontContextHandle,
     backend: BackendType,
@@ -69,6 +70,8 @@ pub impl<'self> FontContext {
                 Cache::new::<FontDescriptor,@mut Font,MonoCache<FontDescriptor,@mut Font>>(10),
             shaper_cache:
                 Cache::new::<FontDescriptor,@Shaper,MonoCache<FontDescriptor,@Shaper>>(10),
+            group_cache:
+                Cache::new::<SpecifiedFontStyle,@FontGroup,MonoCache<SpecifiedFontStyle,@FontGroup>>(10),
             font_list: font_list,
             handle: handle,
             backend: backend,
@@ -93,8 +96,13 @@ pub impl<'self> FontContext {
     }
 
     fn get_resolved_font_for_style(@mut self, style: &SpecifiedFontStyle) -> @FontGroup {
-        // TODO(Issue #178, E): implement a cache of FontGroup instances.
-        self.create_font_group(style)
+        match self.group_cache.find(style) {
+            Some(fg) => return fg,
+            None => ()
+        }
+        let result = self.create_font_group(style);
+        self.group_cache.insert(style, result);
+        result
     }
 
     fn get_font_by_descriptor(&mut self, desc: &FontDescriptor) -> Result<@mut Font, ()> {