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

Source/core/html/forms/InputType.cpp

Index: Source/core/html/forms/InputType.cpp
diff --git a/Source/core/html/forms/InputType.cpp b/Source/core/html/forms/InputType.cpp
index eabbbe9bae142ddff80eb2a1dc308f3b82bef93d..c34cd5a5b8d44fddb15182f0b2f32d8fef7ce44b 100644
--- a/Source/core/html/forms/InputType.cpp
+++ b/Source/core/html/forms/InputType.cpp
@@ -426,7 +426,7 @@ bool InputType::shouldSubmitImplicitly(Event* event)
     return event->isKeyboardEvent() && event->type() == EventTypeNames::keypress && toKeyboardEvent(event)->charCode() == '\r';
 }
 
-Decimal InputType::parseToNumber(const String&, const Decimal& defaultValue) const
+Decimal InputType::parseToNumber(const String&, const String&, const Decimal& defaultValue) const
 {
     ASSERT_NOT_REACHED();
     return defaultValue;
@@ -434,7 +434,7 @@ Decimal InputType::parseToNumber(const String&, const Decimal& defaultValue) con
 
 Decimal InputType::parseToNumberOrNaN(const String& string) const
 {
-    return parseToNumber(string, Decimal::nan());
+    return parseToNumber(string, String(), Decimal::nan());
 }
 
 bool InputType::parseToDateComponents(const String&, DateComponents*) const