Update input[type=range]'s step base handling to match spec.

Source/core/html/forms/RangeInputType.cpp

Index: Source/core/html/forms/RangeInputType.cpp
diff --git a/Source/core/html/forms/RangeInputType.cpp b/Source/core/html/forms/RangeInputType.cpp
index 55066fcc48871707f8d234f19cac199c48c9d8ab..ff9fbad899899c13523e0fc9bfa0b02610357e43 100644
--- a/Source/core/html/forms/RangeInputType.cpp
+++ b/Source/core/html/forms/RangeInputType.cpp
@@ -124,17 +124,18 @@ StepRange RangeInputType::createStepRange(AnyStepHandling anyStepHandling) const
 {
     DEFINE_STATIC_LOCAL(const StepRange::StepDescription, stepDescription, (rangeDefaultStep, rangeDefaultStepBase, rangeStepScaleFactor));
 
+    const Decimal stepBase = findStepBase(rangeDefaultStepBase);
     const Decimal minimum = parseToNumber(element().fastGetAttribute(minAttr), rangeDefaultMinimum);
     const Decimal maximum = ensureMaximum(parseToNumber(element().fastGetAttribute(maxAttr), rangeDefaultMaximum), minimum, rangeDefaultMaximum);
 
     const AtomicString& precisionValue = element().fastGetAttribute(precisionAttr);

[sof, 2014/02/03 18:36:09]

I see there's a use counter against this attribute (and has been for a while);
anyone know (or know who I should ask? :) ) what numbers are being reported?

[tkent, 2014/02/04 00:49:56]

I checked it in the last week, and found the number was unexpectedly high.

[sof, 2014/02/04 06:26:42]

Thanks; how curious.

     if (!precisionValue.isNull()) {
         const Decimal step = equalIgnoringCase(precisionValue, "float") ? Decimal::nan() : 1;
-        return StepRange(minimum, minimum, maximum, step, stepDescription);
+        return StepRange(stepBase, minimum, maximum, step, stepDescription);
     }
 
     const Decimal step = StepRange::parseStep(anyStepHandling, stepDescription, element().fastGetAttribute(stepAttr));
-    return StepRange(minimum, minimum, maximum, step, stepDescription);
+    return StepRange(stepBase, minimum, maximum, step, stepDescription);
 }
 
 bool RangeInputType::isSteppable() const