LibWeb: Disallow spread distance value when parsing text-shadow

`text-shadow` does not support setting a value for spread distance
unlike `box-shadow`.

Libraries/LibWeb/CSS/Parser/Parser.h

@@ -32,6 +32,7 @@
 #include <LibWeb/CSS/StyleValues/AbstractImageStyleValue.h>
 #include <LibWeb/CSS/StyleValues/BasicShapeStyleValue.h>
 #include <LibWeb/CSS/StyleValues/CalculatedStyleValue.h>
+#include <LibWeb/CSS/StyleValues/ShadowStyleValue.h>
 #include <LibWeb/CSS/StyleValues/StyleValue.h>
 #include <LibWeb/CSS/Supports.h>
 #include <LibWeb/CSS/URL.h>
@@ -464,12 +465,8 @@ private:
     RefPtr<StyleValue const> parse_single_repeat_style_value(PropertyID, TokenStream<ComponentValue>&);
     RefPtr<StyleValue const> parse_scrollbar_color_value(TokenStream<ComponentValue>&);
     RefPtr<StyleValue const> parse_scrollbar_gutter_value(TokenStream<ComponentValue>&);
-    enum class AllowInsetKeyword {
-        No,
-        Yes,
-    };
-    RefPtr<StyleValue const> parse_shadow_value(TokenStream<ComponentValue>&, AllowInsetKeyword);
-    RefPtr<StyleValue const> parse_single_shadow_value(TokenStream<ComponentValue>&, AllowInsetKeyword);
+    RefPtr<StyleValue const> parse_shadow_value(TokenStream<ComponentValue>&, ShadowStyleValue::ShadowType);
+    RefPtr<StyleValue const> parse_single_shadow_value(TokenStream<ComponentValue>&, ShadowStyleValue::ShadowType);
     RefPtr<StyleValue const> parse_text_decoration_value(TokenStream<ComponentValue>&);
     RefPtr<StyleValue const> parse_text_decoration_line_value(TokenStream<ComponentValue>&);
     RefPtr<StyleValue const> parse_text_underline_position_value(TokenStream<ComponentValue>&);

Libraries/LibWeb/CSS/Parser/PropertyParsing.cpp

@@ -510,7 +510,7 @@ Parser::ParseErrorOr<NonnullRefPtr<StyleValue const>> Parser::parse_css_value(Pr
             return parsed_value.release_nonnull();
         return ParseError::SyntaxError;
     case PropertyID::BoxShadow:
-        if (auto parsed_value = parse_shadow_value(tokens, AllowInsetKeyword::Yes); parsed_value && !tokens.has_next_token())
+        if (auto parsed_value = parse_shadow_value(tokens, ShadowStyleValue::ShadowType::Normal); parsed_value && !tokens.has_next_token())
             return parsed_value.release_nonnull();
         return ParseError::SyntaxError;
     case PropertyID::ColorScheme:
@@ -747,7 +747,7 @@ Parser::ParseErrorOr<NonnullRefPtr<StyleValue const>> Parser::parse_css_value(Pr
             return parsed_value.release_nonnull();
         return ParseError::SyntaxError;
     case PropertyID::TextShadow:
-        if (auto parsed_value = parse_shadow_value(tokens, AllowInsetKeyword::No); parsed_value && !tokens.has_next_token())
+        if (auto parsed_value = parse_shadow_value(tokens, ShadowStyleValue::ShadowType::Text); parsed_value && !tokens.has_next_token())
             return parsed_value.release_nonnull();
         return ParseError::SyntaxError;
     case PropertyID::TextUnderlinePosition:
@@ -2062,18 +2062,18 @@ RefPtr<StyleValue const> Parser::parse_columns_value(TokenStream<ComponentValue>
         { column_count.release_nonnull(), column_width.release_nonnull(), column_height.release_nonnull() });
 }
 
-RefPtr<StyleValue const> Parser::parse_shadow_value(TokenStream<ComponentValue>& tokens, AllowInsetKeyword allow_inset_keyword)
+RefPtr<StyleValue const> Parser::parse_shadow_value(TokenStream<ComponentValue>& tokens, ShadowStyleValue::ShadowType shadow_type)
 {
     // "none"
     if (auto none = parse_all_as_single_keyword_value(tokens, Keyword::None))
         return none;
 
-    return parse_comma_separated_value_list(tokens, [this, allow_inset_keyword](auto& tokens) {
-        return parse_single_shadow_value(tokens, allow_inset_keyword);
+    return parse_comma_separated_value_list(tokens, [this, shadow_type](auto& tokens) {
+        return parse_single_shadow_value(tokens, shadow_type);
     });
 }
 
-RefPtr<StyleValue const> Parser::parse_single_shadow_value(TokenStream<ComponentValue>& tokens, AllowInsetKeyword allow_inset_keyword)
+RefPtr<StyleValue const> Parser::parse_single_shadow_value(TokenStream<ComponentValue>& tokens, ShadowStyleValue::ShadowType shadow_type)
 {
     auto transaction = tokens.begin_transaction();
 
@@ -2136,13 +2136,17 @@ RefPtr<StyleValue const> Parser::parse_single_shadow_value(TokenStream<Component
             auto maybe_spread_distance = possibly_dynamic_length(tokens.next_token());
             if (!maybe_spread_distance)
                 continue;
+
+            if (shadow_type == ShadowStyleValue::ShadowType::Text)
+                return nullptr;
+
             spread_distance = maybe_spread_distance;
             tokens.discard_a_token();
 
             continue;
         }
 
-        if (allow_inset_keyword == AllowInsetKeyword::Yes && token.is_ident("inset"sv)) {
+        if (shadow_type == ShadowStyleValue::ShadowType::Normal && token.is_ident("inset"sv)) {
             if (placement.has_value())
                 return nullptr;
             placement = ShadowPlacement::Inner;

Libraries/LibWeb/CSS/StyleValues/ShadowStyleValue.h

@@ -22,6 +22,13 @@ enum class ShadowPlacement {
 
 class ShadowStyleValue final : public StyleValueWithDefaultOperators<ShadowStyleValue> {
 public:
+    enum class ShadowType : u8 {
+        // none | <shadow>#
+        Normal,
+        // none | [ <color>? && <length>{2,3} ]#
+        Text
+    };
+
     static ValueComparingNonnullRefPtr<ShadowStyleValue const> create(
         ValueComparingRefPtr<StyleValue const> color,
         ValueComparingNonnullRefPtr<StyleValue const> offset_x,

Libraries/LibWeb/Painting/ShadowPainting.cpp

@@ -83,7 +83,6 @@ void paint_text_shadow(DisplayListRecordingContext& context, PaintableFragment c
         int blur_radius = context.rounded_device_pixels(layer.blur_radius).value();
 
         // Space around the painted text to allow it to blur.
-        // FIXME: Include spread in this once we use that.
         int margin = blur_radius * 2;
         Gfx::IntRect text_rect {
             margin, margin,

Tests/LibWeb/Screenshot/input/text-shadow.html

@@ -35,15 +35,5 @@
   <p>text-shadow: 4px 4px blue, 8px 8px green, 12px 12px yellow</p>
 </div>
 
-<h2>Spread</h2>
-<div class="box" style="text-shadow: 0 0 0 5px magenta">
-  <p>text-shadow: 0 0 0 5px magenta</p>
-</div>
-
-<h2>Spread and blur</h2>
-<div class="box" style="text-shadow: 0 0 10px 5px magenta">
-  <p>text-shadow: 0 0 10px 5px magenta</p>
-</div>
-
 </body>
 </html>

Tests/LibWeb/Text/expected/wpt-import/css/css-text-decor/text-shadow/parsing/text-shadow-invalid.txt

@@ -2,12 +2,11 @@ Harness status: OK
 
 Found 8 tests
 
-7 Pass
-1 Fail
+8 Pass
 Pass	e.style['text-shadow'] = "auto" should not set the property value
 Pass	e.style['text-shadow'] = "10px 20px -30px" should not set the property value
 Pass	e.style['text-shadow'] = "10px" should not set the property value
-Fail	e.style['text-shadow'] = "10px 20px 30px 40px" should not set the property value
+Pass	e.style['text-shadow'] = "10px 20px 30px 40px" should not set the property value
 Pass	e.style['text-shadow'] = "red 10px 20px blue" should not set the property value
 Pass	e.style['text-shadow'] = "10% 20px" should not set the property value
 Pass	e.style['text-shadow'] = "10px 20% 30px" should not set the property value