do not spellcheck data uri's

#WEB-20505 fixed

spellchecker/src/com/intellij/spellchecker/tokenizer/HtmlSpellcheckingStrategy.java

@@ -15,9 +15,11 @@
  */
 package com.intellij.spellchecker.tokenizer;
 
+import com.intellij.psi.ElementManipulators;
 import com.intellij.psi.PsiComment;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.xml.XmlAttributeValue;
+import com.intellij.util.io.URLUtil;
 import org.jetbrains.annotations.NotNull;
 
 public class HtmlSpellcheckingStrategy extends SpellcheckingStrategy {
@@ -25,7 +27,12 @@ public class HtmlSpellcheckingStrategy extends SpellcheckingStrategy {
   @Override
   public Tokenizer getTokenizer(PsiElement element) {
     if (element instanceof PsiComment) return myCommentTokenizer;
-    if (element instanceof XmlAttributeValue) return myXmlAttributeTokenizer;
+    if (element instanceof XmlAttributeValue) {
+      if (URLUtil.isDataUri(ElementManipulators.getValueText(element))) {
+        return EMPTY_TOKENIZER;
+      }
+      return myXmlAttributeTokenizer;
+    }
     return EMPTY_TOKENIZER;
   }
 }

spellchecker/testData/inspection/xmlWithMistakes/test.html

@@ -1,3 +1,4 @@
 <a>test</a>
 <TYPO descr="Typo: In word 'ttest'">ttest</TYPO>
-<div>test</div>
+<div>test</div>
+<img src="data:image/png;base64,foobarbaz…">