LibWeb: Pass font sizes in pt rather than px to Gfx::FontDatabase

Our font database uses point sizes for fonts, and we were passing it
px sizes. This caused all fonts to be 1.333x larger than they should
be on the web. Of course it wasn't always noticeable with bitmap fonts,
but noticeable everywhere with scalable fonts.

Userland/Libraries/LibWeb/CSS/StyleComputer.cpp

@@ -774,7 +774,7 @@ void StyleComputer::compute_font(StyleProperties& style, DOM::Element const* ele
 
     bool bold = weight > Gfx::FontWeight::Regular;
 
-    int size = 10;
+    float font_size_in_px = 10;
 
     if (font_size->is_identifier()) {
         switch (static_cast<const IdentifierStyleValue&>(*font_size).id()) {
@@ -783,14 +783,14 @@ void StyleComputer::compute_font(StyleProperties& style, DOM::Element const* ele
         case CSS::ValueID::Small:
         case CSS::ValueID::Medium:
             // FIXME: Should be based on "user's default font size"
-            size = 10;
+            font_size_in_px = 10;
             break;
         case CSS::ValueID::Large:
         case CSS::ValueID::XLarge:
         case CSS::ValueID::XxLarge:
         case CSS::ValueID::XxxLarge:
             // FIXME: Should be based on "user's default font size"
-            size = 12;
+            font_size_in_px = 12;
             break;
         case CSS::ValueID::Smaller:
         case CSS::ValueID::Larger:
@@ -810,14 +810,14 @@ void StyleComputer::compute_font(StyleProperties& style, DOM::Element const* ele
 
         auto parent_font_size = [&]() -> float {
             if (!parent_element || !parent_element->computed_css_values())
-                return size;
+                return font_size_in_px;
             auto value = parent_element->computed_css_values()->property(CSS::PropertyID::FontSize).value();
             if (value->is_length()) {
                 auto length = static_cast<LengthStyleValue const&>(*value).to_length();
                 if (length.is_absolute() || length.is_relative())
-                    return length.to_px(viewport_rect(), font_metrics, size, root_font_size);
+                    return length.to_px(viewport_rect(), font_metrics, font_size_in_px, root_font_size);
             }
-            return size;
+            return font_size_in_px;
         };
 
         Optional<Length> maybe_length;
@@ -837,7 +837,7 @@ void StyleComputer::compute_font(StyleProperties& style, DOM::Element const* ele
             if (!maybe_length->is_calculated()) {
                 auto px = maybe_length.value().to_px(viewport_rect(), font_metrics, parent_font_size(), root_font_size);
                 if (px != 0)
-                    size = px;
+                    font_size_in_px = px;
             }
         }
     }
@@ -865,12 +865,13 @@ void StyleComputer::compute_font(StyleProperties& style, DOM::Element const* ele
     bool monospace = false;
 
     auto find_font = [&](String const& family) -> RefPtr<Gfx::Font> {
-        font_selector = { family, size, weight, slope };
+        int font_size_in_pt = roundf(font_size_in_px * 0.75f);
+        font_selector = { family, font_size_in_pt, weight, slope };
 
         if (auto found_font = FontCache::the().get(font_selector))
             return found_font;
 
-        if (auto found_font = Gfx::FontDatabase::the().get(family, size, weight, slope, Gfx::Font::AllowInexactSizeMatch::Yes))
+        if (auto found_font = Gfx::FontDatabase::the().get(family, font_size_in_pt, weight, slope, Gfx::Font::AllowInexactSizeMatch::Yes))
             return found_font;
 
         return {};
@@ -926,7 +927,7 @@ void StyleComputer::compute_font(StyleProperties& style, DOM::Element const* ele
 
     FontCache::the().set(font_selector, *found_font);
 
-    style.set_property(CSS::PropertyID::FontSize, LengthStyleValue::create(CSS::Length::make_px(size)));
+    style.set_property(CSS::PropertyID::FontSize, LengthStyleValue::create(CSS::Length::make_px(font_size_in_px)));
     style.set_property(CSS::PropertyID::FontWeight, NumericStyleValue::create_integer(weight));
 
     style.set_computed_font(found_font.release_nonnull());