addMimeType function
Adds additonal mime type for the given extension. Note: it overrides the system default if any.
Example:
addMimeType("woff2", "application/font-woff2");
Implementation
void addMimeType(String extension, String mimeType) {
assert(!extension.startsWith('.'));
assert(mimeType.isNotEmpty);
_mimeResolver.addExtension(extension, mimeType);
}