Makes UTF8 BOM removal in SourceFile unconditional

Some of the callers were incorrect and was already passing true unconditionally which is the behavior introduced by this CL explicitly.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=226521027

src/com/google/javascript/jscomp/SourceFile.java

@@ -47,7 +47,6 @@
 import java.util.Arrays;
 import java.util.Enumeration;
 import java.util.List;
-import java.util.Objects;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 
@@ -173,15 +172,10 @@ String getCodeNoCache() {
   }
 
   void setCode(String sourceCode) {
-    this.setCode(sourceCode, false);
-  }
-
-  void setCode(String sourceCode, boolean removeUtf8Bom) {
-    if (removeUtf8Bom && sourceCode != null && sourceCode.startsWith(UTF8_BOM)) {
-      code = sourceCode.substring(UTF8_BOM.length());
-    } else {
-      code = sourceCode;
-    }
+    code =
+        sourceCode != null && sourceCode.startsWith(UTF8_BOM)
+            ? sourceCode.substring(UTF8_BOM.length())
+            : sourceCode;
     resetLineOffsets();
   }
 
@@ -616,7 +610,7 @@ public synchronized String getCode() throws IOException {
           throw new IOException("Failed to read: " + path + ", is this input UTF-8 encoded?", e);
         }
 
-        super.setCode(cachedCode, Objects.equals(this.getCharset(), inputCharset));
+        super.setCode(cachedCode);
         // Byte Order Mark can be removed by setCode
         cachedCode = super.getCode();
       }
@@ -724,7 +718,7 @@ public synchronized String getCode() throws IOException {
         // Must close the stream or else the cache won't be cleared.
         inputStream.close();
 
-        super.setCode(cachedCode, Objects.equals(this.getCharset(), StandardCharsets.UTF_8));
+        super.setCode(cachedCode);
         // Byte Order Mark can be removed by setCode
         cachedCode = super.getCode();
       }