Implement minlength for <input> and <textarea>.

Source/core/html/HTMLInputElement.h

Index: Source/core/html/HTMLInputElement.h
diff --git a/Source/core/html/HTMLInputElement.h b/Source/core/html/HTMLInputElement.h
index 87d32c0ca5e2b1ec08024e84318c15134965a45e..5fccef09af19c9d5bfd346d4373ea7bb0b392cc5 100644
--- a/Source/core/html/HTMLInputElement.h
+++ b/Source/core/html/HTMLInputElement.h
@@ -62,6 +62,7 @@ public:
     virtual bool rangeOverflow() const override final;
     virtual bool stepMismatch() const override final;
     virtual bool tooLong() const override final;
+    virtual bool tooShort() const override final;
     virtual bool typeMismatch() const override final;
     virtual bool valueMissing() const override final;
     virtual String validationMessage() const override final;
@@ -169,7 +170,9 @@ public:
     KURL src() const;
 
     int maxLength() const;
+    int minLength() const;
     void setMaxLength(int, ExceptionState&);
+    void setMinLength(int, ExceptionState&);
 
     bool multiple() const;
 
@@ -316,6 +319,7 @@ private:
     virtual bool isOutOfRange() const override final;
 
     bool tooLong(const String&, NeedsToCheckDirtyFlag) const;
+    bool tooShort(const String&, NeedsToCheckDirtyFlag) const;
 
     virtual bool supportsPlaceholder() const override final;
     virtual void updatePlaceholderText() override final;
@@ -337,6 +341,7 @@ private:
     void setListAttributeTargetObserver(PassOwnPtrWillBeRawPtr<ListAttributeTargetObserver>);
     void resetListAttributeTargetObserver();
     void parseMaxLengthAttribute(const AtomicString&);
+    void parseMinLengthAttribute(const AtomicString&);
     void updateValueIfNeeded();
 
     // Returns null if this isn't associated with any radio button group.
@@ -354,6 +359,7 @@ private:
     String m_suggestedValue;
     int m_size;
     int m_maxLength;
+    int m_minLength;

[tkent, 2014/10/15 00:50:25]

I don't think we need new data member.  We should try to parse minlength
attribute value on demand.  If it has performance problems, we should introduce
m_minLength then.

[Bartek Nowierski, 2014/10/16 04:55:14]

Someone decided that it's worth doing for maxlength, so just for symmetry we
might as well do it for minlength. The advantage of this approach is that it's
obvious that if one is correct then the other is correct too.

     short m_maxResults;
     bool m_isChecked : 1;
     bool m_reflectsCheckedAttribute : 1;