Implement minlength for <input> and <textarea>.

Source/core/html/FormAssociatedElement.cpp

Index: Source/core/html/FormAssociatedElement.cpp
diff --git a/Source/core/html/FormAssociatedElement.cpp b/Source/core/html/FormAssociatedElement.cpp
index 2c5387d834add4b597c46924351338ce8a92c27b..6975a4585bd4d6d6ea602f4f309dc17ea41e907f 100644
--- a/Source/core/html/FormAssociatedElement.cpp
+++ b/Source/core/html/FormAssociatedElement.cpp
@@ -237,6 +237,11 @@ bool FormAssociatedElement::tooLong() const
     return false;
 }
 
+bool FormAssociatedElement::tooShort() const
+{
+    return false;
+}
+
 bool FormAssociatedElement::typeMismatch() const
 {
     return false;
@@ -245,7 +250,8 @@ bool FormAssociatedElement::typeMismatch() const
 bool FormAssociatedElement::valid() const
 {
     bool someError = typeMismatch() || stepMismatch() || rangeUnderflow() || rangeOverflow()
-        || tooLong() || patternMismatch() || valueMissing() || hasBadInput() || customError();
+        || tooLong() || tooShort() || patternMismatch() || valueMissing() || hasBadInput()
+        || customError();
     return !someError;
 }