SVG doesn't recognize ch units.

Source/core/css/parser/CSSPropertyParser.cpp

 /*
  * Copyright (C) 2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  * Copyright (C) 2012 Intel Corporation. All rights reserved.
  *
@@ skipping 8136 matching lines @@
         return false;
     }
 
     if (validPrimitive) {
         if (id)
             parsedValue = CSSPrimitiveValue::createIdentifier(id);
         else if (value->unit == CSSPrimitiveValue::CSS_STRING)
             parsedValue = CSSPrimitiveValue::create(value->string, (CSSPrimitiveValue::UnitType) value->unit);
         else if (value->unit >= CSSPrimitiveValue::CSS_NUMBER && value->unit <= CSSPrimitiveValue::CSS_KHZ)
             parsedValue = CSSPrimitiveValue::create(value->fValue, (CSSPrimitiveValue::UnitType) value->unit);
-        else if (value->unit == CSSPrimitiveValue::CSS_REMS)
+        else if (value->unit == CSSPrimitiveValue::CSS_REMS || value->unit == CSSPrimitiveValue::CSS_CHS)
             parsedValue = CSSPrimitiveValue::create(value->fValue, (CSSPrimitiveValue::UnitType)value->unit);
         else if (value->unit >= CSSParserValue::Q_EMS)
             parsedValue = CSSPrimitiveValue::createAllowingMarginQuirk(value->fValue, CSSPrimitiveValue::CSS_EMS);
         if (isCalculation(value)) {
             // FIXME calc() http://webkit.org/b/16662 : actually create a CSSPrimitiveValue here, ie
             // parsedValue = CSSPrimitiveValue::create(m_parsedCalculation.release());
             m_parsedCalculation.release();
             parsedValue = nullptr;
         }
         m_valueList->next();
@@ skipping 11 matching lines @@
     CSSParserValue* value = m_valueList->current();
     bool validPrimitive = true;
     while (value) {
         validPrimitive = validUnit(value, FLength | FPercent | FNonNeg, SVGAttributeMode);
         if (!validPrimitive)
             break;
         if (value->id)
             ret->append(CSSPrimitiveValue::createIdentifier(value->id));
         else if (value->unit >= CSSPrimitiveValue::CSS_NUMBER && value->unit <= CSSPrimitiveValue::CSS_KHZ)
             ret->append(CSSPrimitiveValue::create(value->fValue, (CSSPrimitiveValue::UnitType) value->unit));
-        else if (value->unit == CSSPrimitiveValue::CSS_REMS)
+        else if (value->unit == CSSPrimitiveValue::CSS_REMS || value->unit == CSSPrimitiveValue::CSS_CHS)
             ret->append(CSSPrimitiveValue::create(value->fValue, (CSSPrimitiveValue::UnitType)value->unit));
         value = m_valueList->next();
         bool commaConsumed = consumeComma(m_valueList);
         value = m_valueList->current();
         if (commaConsumed && !value)
             return nullptr;
     }
     if (!validPrimitive)
         return nullptr;
     return ret.release();
@@ skipping 285 matching lines @@
         }
     }
 
     if (!list->length())
         return nullptr;
 
     return list.release();
 }
 
 } // namespace blink