Remove TODO about normalizing calc() values at parse time for registered properties

This patch removes a TODO which states we should normalize calc() values
when parsing them for registered properties. I don't recall exactly why
I added this TODO but it doesn't seem that the spec says this needs to
be done. We already simplify calc() values in computation as per spec.

https://drafts.css-houdini.org/css-properties-values-api/

BUG=641877

Review-Url: https://codereview.chromium.org/2399803002
Cr-Commit-Position: refs/heads/master@{#423778}

third_party/WebKit/Source/core/css/CSSSyntaxDescriptor.cpp

@@ -132,7 +132,6 @@ const CSSValue* consumeSingleType(const CSSSyntaxComponent& syntax,
                                   CSSParserTokenRange& range) {
   using namespace CSSPropertyParserHelpers;
 
-  // TODO(timloh): Calc values need to be normalized
   switch (syntax.m_type) {
     case CSSSyntaxType::Ident:
       if (range.peek().type() == IdentToken &&