Remove legacy SELECT popup code.

Source/core/layout/LayoutThemeDefault.cpp

Index: Source/core/layout/LayoutThemeDefault.cpp
diff --git a/Source/core/layout/LayoutThemeDefault.cpp b/Source/core/layout/LayoutThemeDefault.cpp
index c0a678dd4c80dbf172f240cfdbc784ca15325c52..ff69d719bb7293dc52916a544e8016912d1d1ed9 100644
--- a/Source/core/layout/LayoutThemeDefault.cpp
+++ b/Source/core/layout/LayoutThemeDefault.cpp
@@ -109,21 +109,13 @@ Color LayoutThemeDefault::systemColor(CSSValueID cssValueId) const
 // Use the Windows style sheets to match their metrics.
 String LayoutThemeDefault::extraDefaultStyleSheet()
 {
-    String legacyOptionStyle;
-    if (!RuntimeEnabledFeatures::htmlPopupMenuEnabled()) {
-        // Option font must be inherited because we depend on computing the size
-        // of the <select> based on the size of the options, and they must use
-        // the same font for that computation to be correct.
-        legacyOptionStyle = "option { font: inherit !important; }";
-    }
     return LayoutTheme::extraDefaultStyleSheet()
         + loadResourceAsASCIIString("themeWin.css")
         + loadResourceAsASCIIString("themeChromiumSkia.css")
-        + loadResourceAsASCIIString("themeChromium.css")
 #if ENABLE(INPUT_MULTIPLE_FIELDS_UI)
         + loadResourceAsASCIIString("themeInputMultipleFields.css")
 #endif
-        + legacyOptionStyle;
+        + loadResourceAsASCIIString("themeChromium.css");
 }
 
 String LayoutThemeDefault::extraQuirksStyleSheet()