Here are the classes, structs, unions and interfaces with brief descriptions:

CAbstractWorker
CApplicationCache
CAttr
CAudioTrack
CAudioTrackList
CAutocompleteErrorEvent
CBarProp
CBeforeUnloadEvent
Cbinding
Cbinding_interface
CBroadcastChannel
CCanvasDrawingStyles
CCanvasGradient
CCanvasPathMethods
CCanvasPattern
CCanvasProxy
CCanvasRenderingContext2D
CCharacterData
CChildNode
CCloseEvent
CComment
CCompositionEvent
CConsole
CCustomEvent
CDataTransfer
CDataTransferItem
CDataTransferItemList
CDedicatedWorkerGlobalScope
CDocument
CDocumentFragment
CDocumentType
CDOMElementMap
CDOMImplementation
CDOMSettableTokenList
CDOMStringMap
CDOMTokenList
CDragEvent
CDrawingStyle
CElement
CElementContentEditable
CErrorEvent
CEvent
CEventListener
CEventSource
CEventTarget
CExternal
CFocusEvent
Cgenbind_node
CGlobalEventHandlers
CHashChangeEvent
CHistory
CHTMLAllCollection
CHTMLAnchorElement
CHTMLAppletElement
CHTMLAreaElement
CHTMLAudioElement
CHTMLBaseElement
CHTMLBodyElement
CHTMLBRElement
CHTMLButtonElement
CHTMLCanvasElement
CHTMLCollection
CHTMLDataElement
CHTMLDataListElement
CHTMLDetailsElement
CHTMLDialogElement
CHTMLDirectoryElement
CHTMLDivElement
CHTMLDListElement
CHTMLElement
CHTMLEmbedElement
CHTMLFieldSetElement
CHTMLFontElement
CHTMLFormControlsCollection
CHTMLFormElement
CHTMLFrameElement
CHTMLFrameSetElement
CHTMLHeadElement
CHTMLHeadingElement
CHTMLHRElement
CHTMLHtmlElement
CHTMLIFrameElement
CHTMLImageElement
CHTMLInputElement
CHTMLKeygenElement
CHTMLLabelElement
CHTMLLegendElement
CHTMLLIElement
CHTMLLinkElement
CHTMLMapElement
CHTMLMarqueeElement
CHTMLMediaElement
CHTMLMenuElement
CHTMLMenuItemElement
CHTMLMetaElement
CHTMLMeterElement
CHTMLModElement
CHTMLObjectElement
CHTMLOListElement
CHTMLOptGroupElement
CHTMLOptionElement
CHTMLOptionsCollection
CHTMLOutputElement
CHTMLParagraphElement
CHTMLParamElement
CHTMLPictureElement
CHTMLPreElement
CHTMLProgressElement
CHTMLPropertiesCollection
CHTMLQuoteElement
CHTMLScriptElement
CHTMLSelectElement
CHTMLSourceElement
CHTMLSpanElement
CHTMLStyleElement
CHTMLTableCaptionElement
CHTMLTableCellElement
CHTMLTableColElement
CHTMLTableDataCellElement
CHTMLTableElement
CHTMLTableHeaderCellElement
CHTMLTableRowElement
CHTMLTableSectionElement
CHTMLTemplateElement
CHTMLTextAreaElement
CHTMLTimeElement
CHTMLTitleElement
CHTMLTrackElement
CHTMLUListElement
CHTMLUnknownElement
CHTMLVideoElement
CImageBitmap
CImageBitmapFactories
CImageData
Cir
Cir_attribute_entry
Cir_constant_entry
Cir_dictionary_entry
Cir_entry
Cir_interface_entry
Cir_operation_argument_entry
Cir_operation_entry
Cir_operation_overload_entry
Cir_type_entry
CKeyboardEvent
CLocation
CMediaController
CMediaError
CMessageChannel
CMessageEvent
CMessagePort
CMimeType
CMimeTypeArray
CMouseEvent
CMutationEvent
CMutationObserver
CMutationRecord
CNamedNodeMap
CNavigator
CNavigatorContentUtils
CNavigatorID
CNavigatorLanguage
CNavigatorOnLine
CNavigatorPlugins
CNavigatorStorageUtils
CNode
CNodeFilter
CNodeIterator
CNodeList
CNonDocumentTypeChildNode
CNonElementParentNode
CNSGENBIND_LTYPE
CNSGENBIND_STYPE
Copctx
Coptions
CPageTransitionEvent
CParentNode
CPlugin
CPluginArray
CPopStateEvent
CPortCollection
CProcessingInstruction
CPropertyNodeList
CRadioNodeList
CRange
CRelatedEvent
CSharedWorker
CSharedWorkerGlobalScope
CStorage
CStorageEvent
CText
CTextMetrics
CTextTrack
CTextTrackCue
CTextTrackCueList
CTextTrackList
CTimeRanges
CTouch
CTrackEvent
CTreeWalker
CUIEvent
CURL
CURLSearchParams
CURLUtils
CURLUtilsReadOnly
CURLUtilsSearchParams
CValidityState
CVideoTrack
CVideoTrackList
CWEBIDL_LTYPE
Cwebidl_node
CWEBIDL_STYPE
CWheelEvent
CWindow
CWindowBase64
CWindowEventHandlers
CWindowLocalStorage
CWindowModal
CWindowSessionStorage
CWindowTimers
CWorker
CWorkerGlobalScope
CWorkerLocation
CWorkerNavigator
CXMLDocument
Cyy_buffer_state
Cyy_trans_info
Cyyalloc
CYYLTYPE
Cyypcontext_t