[Omit needless words] Strip context from "set" methods.

Fixes rdar://problem/25750367.

lib/Basic/StringExtras.cpp

@@ -1219,6 +1219,19 @@ bool swift::omitNeedlessWords(StringRef &baseName,
     return lowercaseAcronymsForReturn();
   }
 
+  if (camel_case::getFirstWord(baseName) == "set") {
+    StringRef newBaseName = ::omitNeedlessWords(
+                              baseName,
+                              contextType,
+                              NameRole::Property,
+                              allPropertyNames,
+                              scratch);
+    if (newBaseName != baseName) {
+      baseName = newBaseName;
+      anyChanges = true;
+    }
+  }
+
   // If needed, split the base name.
   if (!argNames.empty() &&
       splitBaseName(baseName, argNames[0], paramTypes[0], firstParamName))

test/IDE/Inputs/custom-modules/OmitNeedlessWords.h

@@ -32,6 +32,8 @@
 -(void)drawGreebies:(nonnull SEGreebieArray*)greebies;
 -(void)doSomethingBoundBy:(NSInteger)value;
 -(void)doSomethingSeparatedBy:(NSInteger)value;
++(nonnull OmitNeedlessWords *)currentOmitNeedlessWords;
++(void)setCurrentOmitNeedlessWords:(nonnull OmitNeedlessWords *)value;
 @end
 
 @interface ABCDoodle : NSObject

test/IDE/print_omit_needless_words.swift

@@ -308,6 +308,10 @@
 // "separated by"
 // CHECK-OMIT-NEEDLESS-WORDS: func doSomething(separatedBy: Int)
 
+// "Property"-like stripping for "set" methods.
+// CHECK-OMIT-NEEDLESS-WORDS: class func current() -> OmitNeedlessWords
+// CHECK-OMIT-NEEDLESS-WORDS: class func setCurrent(_: OmitNeedlessWords)
+
 // Property-name sensitivity in the base name "Self" stripping.
 // CHECK-OMIT-NEEDLESS-WORDS: func addDoodle(_: ABCDoodle)