Bug 120451 – Make SVGTextContentElement methods behave consistently with Firefox and IE

• Component: SVG
• Status: RESOLVED FIXED

[Ryosuke Niwa]

Consider merging https://chromium.googlesource.com/chromium/blink/+/f28cb3ba700c3faf578046a6b7fa7f9cf17d04c7

Make SVGTextContentElement methods behave consistently with Firefox 23 and
IE10:
- We should not throw when negative values are passed in arguments as long
  as they wrap to a valid positive index.
- Arguments should be mandatory

Also fixed a bug in SVGTextContentElement.getSubStringLength() where the
wrong result would be returned if the nchars argument was
too large due to an overflow. To avoid this issue, we clamp the nchars
value to (numberOfChars - charnum) similarly to what is done in
SVGTextContentElement.selectSubString(), and as per the specification:
http://www.w3.org/TR/SVG2/text.html#__svg__SVGTextContentElement__getSubStringLength

[Ahmad Saleem]

We should also at the same time fix this - https://src.chromium.org/viewvc/blink?view=revision&revision=169682

[Ahmad Saleem]

I looked into commit in Comment 0:

Rather than merging, we should just align IDL with spec:

https://svgwg.org/svg2-draft/text.html#InterfaceSVGTextContentElement

I think cpp change is already taken care of here - https://searchfox.org/wubkat/source/Source/WebCore/svg/SVGTextContentElement.cpp#75

______

I just local change and it progresses some WPT tests as well. Adding WPTImpact tag.

Will attach screenshot of my patch as well.

[Ahmad Saleem]

Created attachment 465875 [details]
GitHub patch modifying '.idl' file (compiles)

[EWS]

Committed 262964@main (7a9711ddf39e): <https://commits.webkit.org/262964@main>

Reviewed commits have been landed. Closing PR #12675 and removing active labels.

[Radar WebKit Bug Importer]

<rdar://problem/108049143>