MIME type predicates and case-insensitive matching.

Source/core/dom/DOMImplementation.cpp

Index: Source/core/dom/DOMImplementation.cpp
diff --git a/Source/core/dom/DOMImplementation.cpp b/Source/core/dom/DOMImplementation.cpp
index ac17ccb749655871ed4312d8d64dc5efab282290..03be1f060801a1ad1d1c868f34a76154f64adc91 100644
--- a/Source/core/dom/DOMImplementation.cpp
+++ b/Source/core/dom/DOMImplementation.cpp
@@ -233,24 +233,31 @@ PassRefPtr<CSSStyleSheet> DOMImplementation::createCSSStyleSheet(const String&,
     return sheet;
 }
 
+static bool equalToUpperCaseASCIIIgnoringCase(char asciiUpper, UChar u)
+{
+    return static_cast<UChar>(asciiUpper) == (u & static_cast<UChar>(~0x20));

[jochen (gone - plz use gerrit), 2014/01/03 11:31:09]

nit. use toASCIIUpper() 

+}
+
 bool DOMImplementation::isXMLMIMEType(const String& mimeType)
 {
-    if (mimeType == "text/xml" || mimeType == "application/xml" || mimeType == "text/xsl")
+    if (equalIgnoringCase(mimeType, "text/xml")
+        || equalIgnoringCase(mimeType, "application/xml")
+        || equalIgnoringCase(mimeType, "text/xsl"))
         return true;
 
-    // Per RFCs 3023 and 2045 a mime type is of the form:
+    // Per RFCs 3023 and 2045, an XML MIME type is of the form:
     // ^[0-9a-zA-Z_\\-+~!$\\^{}|.%'`#&*]+/[0-9a-zA-Z_\\-+~!$\\^{}|.%'`#&*]+\+xml$
 
     int length = mimeType.length();
     if (length < 7)
         return false;
 
-    if (mimeType[0] == '/' ||
-        mimeType[length - 5] == '/' ||
-        mimeType[length - 4] != '+' ||
-        mimeType[length - 3] != 'x' ||
-        mimeType[length - 2] != 'm' ||
-        mimeType[length - 1] != 'l')
+    if (mimeType[0] == '/'
+        || mimeType[length - 5] == '/'
+        || mimeType[length - 4] != '+'
+        || !equalToUpperCaseASCIIIgnoringCase('X', mimeType[length - 3])

[jochen (gone - plz use gerrit), 2014/01/03 11:31:09]

why not !mimeType.endsWith("+xml", true)

[sof, 2014/01/03 13:51:02]

Nice; switched to this simpler form instead (removing the added helper in the
process.)

+        || !equalToUpperCaseASCIIIgnoringCase('M', mimeType[length - 2])
+        || !equalToUpperCaseASCIIIgnoringCase('L', mimeType[length - 1]))
         return false;
 
     bool hasSlash = false;