Sync from Google (#26803)

* Internal refactor

PiperOrigin-RevId: 286440062

* Internal refactor

PiperOrigin-RevId: 286445112

* Internal refactor

PiperOrigin-RevId: 286467041

* Internal refactor

PiperOrigin-RevId: 286933741

* Internal refactor

PiperOrigin-RevId: 287221103

* revert entities.json

Co-authored-by: Amaltas <amaltas@amaltas.org>

validator/htmlparser/bin/casetablegen.cc

@@ -115,7 +115,7 @@ int main(int argc, char** argv) {
   options.white_space_transform =
       htmlparser::FileReadOptions::LineTransforms::StripWhitespace();
   if (!htmlparser::FileUtil::ReadFileLines(
-          options, "htmlparser/data/CaseFolding.txt", &lines)) {
+          options, "testdata/go/CaseFolding.txt", &lines)) {
     std::cerr << "Error reading input file." << std::endl;
     return EXIT_FAILURE;
   }

validator/htmlparser/data/extras.txt

@@ -14,12 +14,82 @@ desc
 face
 font
 # HTML is case-insensitive, but SVG-embedded-in-HTML is case-sensitive.
+altGlyph
+altGlyphItem
+altglyph
+altglyphdef
+altGlyphDef
+altglyphitem
+animateColor
+animateMotion
+animateTransform
+animatecolor
+animatemotion
+animatetransform
+clipPath
+clippath
+definitionURL
+definitionurl
+feBlend
+feColorMatrix
+feComponentTransfer
+feComposite
+feConvolveMatrix
+feDiffuseLighting
+feDisplacementMap
+feDistantLight
+feFlood
+feFuncA
+feFuncB
+feFuncG
+feFuncR
+feGaussianBlur
+feImage
+feMerge
+feMergeNode
+feMorphology
+feOffset
+fePointLight
+feSpecularLighting
+feSpotLight
+feTile
+feTurbulence
+feblend
+fecolormatrix
+fecomponenttransfer
+fecomposite
+feconvolvematrix
+fediffuselighting
+fedisplacementmap
+fedistantlight
+feflood
+fefunca
+fefuncb
+fefuncg
+fefuncr
+fegaussianblur
+feimage
+femerge
+femergenode
+femorphology
+feoffset
+fepointlight
+fespecularlighting
+fespotlight
+fetile
+feturbulence
 foreignObject
+foreignObject
+foreignobject
 foreignobject
 frame
 frameset
+glyphRef
+glyphref
 image
 isindex
+linearGradient
+lineargradient
 listing
 malignmark
 marquee
@@ -33,14 +103,143 @@ mtext
 nobr
 noembed
 noframes
+path
 plaintext
 prompt
 public
+radialGradient
+radialgradient
 rb
 rtc
 spacer
 strike
 svg
 system
+textPath
+textpath
 tt
 xmp
+attributename
+attributeName
+attributetype
+attributeType
+basefrequency
+baseFrequency
+baseprofile
+baseProfile
+calcmode
+calcMode
+clippathunits
+clipPathUnits
+contentscripttype
+contentScriptType
+contentstyletype
+contentStyleType
+diffuseconstant
+diffuseConstant
+edgemode
+edgeMode
+externalresourcesrequired
+externalResourcesRequired
+filterres
+filterRes
+filterunits
+filterUnits
+glyphref
+glyphRef
+gradienttransform
+gradientTransform
+gradientunits
+gradientUnits
+kernelmatrix
+kernelMatrix
+kernelunitlength
+kernelUnitLength
+keypoints
+keyPoints
+keysplines
+keySplines
+keytimes
+keyTimes
+lengthadjust
+lengthAdjust
+limitingconeangle
+limitingConeAngle
+markerheight
+markerHeight
+markerunits
+markerUnits
+markerwidth
+markerWidth
+maskcontentunits
+maskContentUnits
+maskunits
+maskUnits
+numoctaves
+numOctaves
+pathlength
+pathLength
+patterncontentunits
+patternContentUnits
+patterntransform
+patternTransform
+patternunits
+patternUnits
+pointsatx
+pointsAtX
+pointsaty
+pointsAtY
+pointsatz
+pointsAtZ
+preservealpha
+preserveAlpha
+preserveaspectratio
+preserveAspectRatio
+primitiveunits
+primitiveUnits
+refx
+refX
+refy
+refY
+repeatcount
+repeatCount
+repeatdur
+repeatDur
+requiredextensions
+requiredExtensions
+requiredfeatures
+requiredFeatures
+specularconstant
+specularConstant
+specularexponent
+specularExponent
+spreadmethod
+spreadMethod
+startoffset
+startOffset
+stddeviation
+stdDeviation
+stitchtiles
+stitchTiles
+surfacescale
+surfaceScale
+systemlanguage
+systemLanguage
+tablevalues
+tableValues
+targetx
+targetX
+targety
+targetY
+textlength
+textLength
+viewbox
+viewBox
+viewtarget
+viewTarget
+xchannelselector
+xChannelSelector
+ychannelselector
+yChannelSelector
+zoomandpan
+zoomAndPan