Derive the step base for an input element as (now) specified.

Source/core/html/forms/TimeInputType.cpp

Index: Source/core/html/forms/TimeInputType.cpp
diff --git a/Source/core/html/forms/TimeInputType.cpp b/Source/core/html/forms/TimeInputType.cpp
index cc135bd2e8a7c510ff034cf64899e6a2dea1a1b0..58afdb9c28b24b765bb9f7581ebd05637dd9e5c9 100644
--- a/Source/core/html/forms/TimeInputType.cpp
+++ b/Source/core/html/forms/TimeInputType.cpp
@@ -95,9 +95,9 @@ StepRange TimeInputType::createStepRange(AnyStepHandling anyStepHandling) const
 {
     DEFINE_STATIC_LOCAL(const StepRange::StepDescription, stepDescription, (timeDefaultStep, timeDefaultStepBase, timeStepScaleFactor, StepRange::ScaledStepValueShouldBeInteger));
 
-    const Decimal stepBase = parseToNumber(element().fastGetAttribute(minAttr), 0);
-    const Decimal minimum = parseToNumber(element().fastGetAttribute(minAttr), Decimal::fromDouble(DateComponents::minimumTime()));
-    const Decimal maximum = parseToNumber(element().fastGetAttribute(maxAttr), Decimal::fromDouble(DateComponents::maximumTime()));
+    const Decimal stepBase = parseToNumber(element().fastGetAttribute(minAttr), element().fastGetAttribute(valueAttr), 0);
+    const Decimal minimum = parseToNumber(element().fastGetAttribute(minAttr), String(), Decimal::fromDouble(DateComponents::minimumTime()));
+    const Decimal maximum = parseToNumber(element().fastGetAttribute(maxAttr), String(), Decimal::fromDouble(DateComponents::maximumTime()));
     const Decimal step = StepRange::parseStep(anyStepHandling, stepDescription, element().fastGetAttribute(stepAttr));
     return StepRange(stepBase, minimum, maximum, step, stepDescription);
 }