Add missing .h files to .gn files that have a .cc file next to it in the gn file already.

third_party/WebKit/Source/core/css/BUILD.gn

Index: third_party/WebKit/Source/core/css/BUILD.gn
diff --git a/third_party/WebKit/Source/core/css/BUILD.gn b/third_party/WebKit/Source/core/css/BUILD.gn
index da41d119711dd6080441086b5282871fef08f062..cbb07da89ea170b7f3ca7a2265188df4130e0988 100644
--- a/third_party/WebKit/Source/core/css/BUILD.gn
+++ b/third_party/WebKit/Source/core/css/BUILD.gn
@@ -10,9 +10,11 @@ blink_core_sources("css") {
     "ActiveStyleSheets.cpp",
     "ActiveStyleSheets.h",
     "BasicShapeFunctions.cpp",
+    "BasicShapeFunctions.h",
     "BinaryDataFontFaceSource.cpp",
     "BinaryDataFontFaceSource.h",
     "CSSBasicShapeValues.cpp",
+    "CSSBasicShapeValues.h",
     "CSSBorderImage.cpp",
     "CSSBorderImage.h",
     "CSSBorderImageSliceValue.cpp",
@@ -22,6 +24,7 @@ blink_core_sources("css") {
     "CSSColorValue.cpp",
     "CSSColorValue.h",
     "CSSComputedStyleDeclaration.cpp",
+    "CSSComputedStyleDeclaration.h",
     "CSSConditionRule.cpp",
     "CSSConditionRule.h",
     "CSSContentDistributionValue.cpp",
@@ -31,6 +34,7 @@ blink_core_sources("css") {
     "CSSCrossfadeValue.cpp",
     "CSSCrossfadeValue.h",
     "CSSCursorImageValue.cpp",
+    "CSSCursorImageValue.h",
     "CSSCustomFontData.h",
     "CSSCustomIdentValue.cpp",
     "CSSCustomIdentValue.h",
@@ -72,8 +76,11 @@ blink_core_sources("css") {
     "CSSIdentifierValue.cpp",
     "CSSIdentifierValue.h",
     "CSSImageGeneratorValue.cpp",
+    "CSSImageGeneratorValue.h",
     "CSSImageSetValue.cpp",
+    "CSSImageSetValue.h",
     "CSSImageValue.cpp",
+    "CSSImageValue.h",
     "CSSImportRule.cpp",
     "CSSImportRule.h",
     "CSSInheritedValue.cpp",
@@ -106,12 +113,15 @@ blink_core_sources("css") {
     "CSSPrimitiveValue.h",
     "CSSPrimitiveValueMappings.h",
     "CSSProperty.cpp",
+    "CSSProperty.h",
     "CSSPropertyEquality.cpp",
     "CSSPropertyEquality.h",
     "CSSPropertySourceData.cpp",
+    "CSSPropertySourceData.h",
     "CSSQuadValue.cpp",
     "CSSQuadValue.h",
     "CSSReflectValue.cpp",
+    "CSSReflectValue.h",
     "CSSRule.cpp",
     "CSSRule.h",
     "CSSRuleList.cpp",
@@ -119,6 +129,7 @@ blink_core_sources("css") {
     "CSSSegmentedFontFace.cpp",
     "CSSSegmentedFontFace.h",
     "CSSSelector.cpp",
+    "CSSSelector.h",
     "CSSSelectorList.cpp",
     "CSSSelectorList.h",
     "CSSShadowValue.cpp",
@@ -148,8 +159,10 @@ blink_core_sources("css") {
     "CSSUnsetValue.cpp",
     "CSSUnsetValue.h",
     "CSSValue.cpp",
+    "CSSValue.h",
     "CSSValueIDMappings.h",
     "CSSValueList.cpp",
+    "CSSValueList.h",
     "CSSValuePair.cpp",
     "CSSValuePair.h",
     "CSSValuePool.cpp",
@@ -201,8 +214,11 @@ blink_core_sources("css") {
     "MediaQueryMatcher.cpp",
     "MediaQueryMatcher.h",
     "MediaValues.cpp",
+    "MediaValues.h",
     "MediaValuesCached.cpp",
+    "MediaValuesCached.h",
     "MediaValuesDynamic.cpp",
+    "MediaValuesDynamic.h",
     "MediaValuesInitialViewport.cpp",
     "MediaValuesInitialViewport.h",
     "PageRuleCollector.cpp",
@@ -326,9 +342,11 @@ blink_core_sources("css") {
     "parser/CSSParserImpl.h",
     "parser/CSSParserMode.h",
     "parser/CSSParserObserverWrapper.cpp",
+    "parser/CSSParserObserverWrapper.h",
     "parser/CSSParserSelector.cpp",
     "parser/CSSParserSelector.h",
     "parser/CSSParserToken.cpp",
+    "parser/CSSParserToken.h",
     "parser/CSSParserTokenRange.cpp",
     "parser/CSSParserTokenRange.h",
     "parser/CSSPropertyParser.cpp",
@@ -340,15 +358,21 @@ blink_core_sources("css") {
     "parser/CSSSupportsParser.cpp",
     "parser/CSSSupportsParser.h",
     "parser/CSSTokenizer.cpp",
+    "parser/CSSTokenizer.h",
     "parser/CSSTokenizerInputStream.cpp",
+    "parser/CSSTokenizerInputStream.h",
     "parser/CSSVariableParser.cpp",
     "parser/CSSVariableParser.h",
     "parser/FontVariantLigaturesParser.h",
     "parser/FontVariantNumericParser.h",
     "parser/MediaQueryBlockWatcher.cpp",
+    "parser/MediaQueryBlockWatcher.h",
     "parser/MediaQueryParser.cpp",
+    "parser/MediaQueryParser.h",
     "parser/SizesAttributeParser.cpp",
+    "parser/SizesAttributeParser.h",
     "parser/SizesCalcParser.cpp",
+    "parser/SizesCalcParser.h",
     "properties/CSSPropertyAPIAlignItems.cpp",
     "properties/CSSPropertyAPIAlignOrJustifyContent.cpp",
     "properties/CSSPropertyAPIAlignOrJustifySelf.cpp",