[css-typed-om] Ignore surrounding whitespace in CSSNumericValue.parse.

Fixes an issue where CSSNumericValue.parse considers valid strings
surrounded by whitespace to be invalid.

Bug: 844290
Change-Id: I4c40044631276a611ef9a56aac21ddf09316a550
Reviewed-on: https://chromium-review.googlesource.com/1065532Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560207}

third_party/WebKit/LayoutTests/external/wpt/css/css-typed-om/stylevalue-subclasses/numeric-objects/parse.tentative.html

@@ -23,4 +23,8 @@ test(() => {
   assert_throws(new SyntaxError(), () => CSSNumericValue.parse('calc(calc(1px * 2s) + 3%)'));
 }, 'Parsing a calc with incompatible units throws a SyntaxError');
 
+test(() => {
+  assert_style_value_equals(new CSSUnitValue(1, 'px'), CSSNumericValue.parse(' 1px  '));
+}, 'Parsing ignores surrounding spaces');
+
 </script>

third_party/blink/renderer/core/css/cssom/css_numeric_value.cc

@@ -205,7 +205,9 @@ CSSNumericValue* CSSNumericValue::parse(const String& css_text,
                                         ExceptionState& exception_state) {
   CSSTokenizer tokenizer(css_text);
   CSSParserTokenStream stream(tokenizer);
+  stream.ConsumeWhitespace();
   auto range = stream.ConsumeUntilPeekedTypeIs<>();
+  stream.ConsumeWhitespace();
   if (!stream.AtEnd()) {
     exception_state.ThrowDOMException(kSyntaxError, "Invalid math expression");
     return nullptr;
@@ -215,7 +217,7 @@ CSSNumericValue* CSSNumericValue::parse(const String& css_text,
     case kNumberToken:
     case kPercentageToken:
     case kDimensionToken: {
-      const auto token = range.Consume();
+      const auto token = range.ConsumeIncludingWhitespace();
       if (!range.AtEnd())
         break;
       return CSSUnitValue::Create(token.NumericValue(), token.GetUnitType());