Bug 1144743 part 1. Add a hasPollutedGlobalScope flag to scripts. r=luke

js/src/jsscript.cpp

@@ -576,7 +576,8 @@ js::XDRScript(XDRState<mode> *xdr, HandleObject enclosingScope, HandleScript enc
         IsCompileAndGo,
         HasSingleton,
         TreatAsRunOnce,
-        HasLazyScript
+        HasLazyScript,
+        HasPollutedGlobalScope,
     };
 
     uint32_t length, lineno, column, nslots, staticLevel;
@@ -694,6 +695,8 @@ js::XDRScript(XDRState<mode> *xdr, HandleObject enclosingScope, HandleScript enc
             scriptBits |= (1 << TreatAsRunOnce);
         if (script->isRelazifiable())
             scriptBits |= (1 << HasLazyScript);
+        if (script->hasPollutedGlobalScope())
+            scriptBits |= (1 << HasPollutedGlobalScope);
     }
 
     if (!xdr->codeUint32(&prologLength))
@@ -811,6 +814,8 @@ js::XDRScript(XDRState<mode> *xdr, HandleObject enclosingScope, HandleScript enc
             script->hasSingletons_ = true;
         if (scriptBits & (1 << TreatAsRunOnce))
             script->treatAsRunOnce_ = true;
+        if (scriptBits & (1 << HasPollutedGlobalScope))
+            script->hasPollutedGlobalScope_ = true;
 
         if (scriptBits & (1 << IsLegacyGenerator)) {
             MOZ_ASSERT(!(scriptBits & (1 << IsStarGenerator)));

js/src/jsscript.h

@@ -918,6 +918,11 @@ class JSScript : public js::gc::TenuredCell
     // See Parser::compileAndGo.
     bool compileAndGo_:1;
 
+    // True if the script has a non-syntactic scope on its dynamic scope chain.
+    // That is, there are objects about which we know nothing between the
+    // outermost syntactic scope and the global.
+    bool hasPollutedGlobalScope_:1;
+
     // see Parser::selfHostingMode.
     bool selfHosted_:1;
 
@@ -1143,6 +1148,10 @@ class JSScript : public js::gc::TenuredCell
         return compileAndGo_;
     }
 
+    bool hasPollutedGlobalScope() const {
+        return hasPollutedGlobalScope_;
+    }
+
     bool selfHosted() const { return selfHosted_; }
     bool bindingsAccessedDynamically() const { return bindingsAccessedDynamically_; }
     bool funHasExtensibleScope() const {

js/src/vm/Xdr.h

@@ -29,7 +29,7 @@ namespace js {
  *
  *  https://developer.mozilla.org/en-US/docs/SpiderMonkey/Internals/Bytecode
  */
-static const uint32_t XDR_BYTECODE_VERSION_SUBTRAHEND = 259;
+static const uint32_t XDR_BYTECODE_VERSION_SUBTRAHEND = 260;
 static const uint32_t XDR_BYTECODE_VERSION =
     uint32_t(0xb973c0de - XDR_BYTECODE_VERSION_SUBTRAHEND);