Replace GrStringBuilder with SkString. First step in cleaning up the shader generator. Slight performance hit when creating a new shader (<10% of total shader gen time on my Windows box is spent in building our string before handing it to GL). Much of this can be recovered by better usage pattern of SkString in coming revisions.

Review URL: http://codereview.appspot.com/4465053/ 



git-svn-id: http://skia.googlecode.com/svn/trunk@1266 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkString.cpp b/src/core/SkString.cpp
index 49182ea..f461a7a 100644
--- a/src/core/SkString.cpp
+++ b/src/core/SkString.cpp
@@ -317,6 +317,15 @@
     return *this;
 }
 
+SkString& SkString::operator=(const char text[]) {
+    this->validate();
+
+    SkString tmp(text);
+    this->swap(tmp);
+
+    return *this;
+}
+
 void SkString::reset() {
     this->validate();