Remove lots of dead web/ classes.

sky/engine/web/BUILD.gn

Index: sky/engine/web/BUILD.gn
diff --git a/sky/engine/web/BUILD.gn b/sky/engine/web/BUILD.gn
index 4bd2c15a61c588298c45bb9bd88f6b2830ed43b0..5ec70745a9028b8aab4ce135f66b4ac59bbad164 100644
--- a/sky/engine/web/BUILD.gn
+++ b/sky/engine/web/BUILD.gn
@@ -58,20 +58,9 @@ component("web") {
     "WebArrayBufferView.cpp",
     "WebCache.cpp",
     "WebCachedURLRequest.cpp",
-    "WebColorSuggestion.cpp",
     "WebCustomElement.cpp",
-    "WebDOMCustomEvent.cpp",
-    "WebDOMError.cpp",
-    "WebDOMEvent.cpp",
-    "WebDOMMouseEvent.cpp",
-    "WebDOMProgressEvent.cpp",
-    "WebDOMResourceProgressEvent.cpp",
-    "WebDatabase.cpp",
     "WebDocument.cpp",
-    "WebDocumentType.cpp",
     "WebElement.cpp",
-    "WebEntities.cpp",
-    "WebEntities.h",
     "WebFontDescription.cpp",
     "WebFontImpl.cpp",
     "WebFontImpl.h",
@@ -88,20 +77,15 @@ component("web") {
     "WebLocalFrameImpl.cpp",
     "WebLocalFrameImpl.h",
     "WebNode.cpp",
-    "WebPerformance.cpp",
     "WebRange.cpp",
     "WebRuntimeFeatures.cpp",
-    "WebScopedMicrotaskSuppression.cpp",
     "WebScopedUserGesture.cpp",
-    "WebScopedWindowFocusAllowedIndicator.cpp",
     "WebScriptBindings.cpp",
     "WebScriptController.cpp",
     "WebScrollbarThemePainter.cpp",
     "WebSecurityPolicy.cpp",
-    "WebSerializedScriptValue.cpp",
     "WebSettingsImpl.cpp",
     "WebSettingsImpl.h",
-    "WebSurroundingText.cpp",
     "WebTextCheckingCompletionImpl.cpp",
     "WebTextCheckingCompletionImpl.h",
     "WebTextCheckingResult.cpp",